diff --git a/java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java b/java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java
index 0f6ab30..2711d24 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java
@@ -340,10 +340,6 @@
         mState.onCodeInput(code, mLatinIME.getCurrentAutoCapsState());
     }
 
-    private boolean isShowingMainKeyboard() {
-        return null != mKeyboardView && mKeyboardView.isShown();
-    }
-
     public boolean isShowingEmojiPalettes() {
         return mEmojiPalettesView != null && mEmojiPalettesView.isShown();
     }
@@ -376,10 +372,6 @@
         }
     }
 
-    public boolean isShowingMainKeyboardOrEmojiPalettes() {
-        return isShowingMainKeyboard() || isShowingEmojiPalettes();
-    }
-
     public View onCreateInputView(final boolean isHardwareAcceleratedDrawingEnabled) {
         if (mKeyboardView != null) {
             mKeyboardView.closing();
diff --git a/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java b/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
index 2dba713..cd18a6b 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
@@ -36,6 +36,7 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Locale;
+import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CountDownLatch;
@@ -142,7 +143,8 @@
 
     @UsedForTesting
     public DictionaryFacilitatorForSuggest(final Context context, final Locale locale,
-            final ArrayList<String> dictionaryTypes, final HashMap<String, File> dictionaryFiles) {
+            final ArrayList<String> dictionaryTypes, final HashMap<String, File> dictionaryFiles,
+            final Map<String, Map<String, String>> additionalDictAttributes) {
         mContext = context;
         mLocale = locale;
         mLatchForWaitingLoadingMainDictionary = new CountDownLatch(0);
@@ -159,6 +161,10 @@
                 userHistoryDictionary.reloadDictionaryIfRequired();
                 userHistoryDictionary.waitAllTasksForTests();
                 setUserHistoryDictionary(userHistoryDictionary);
+                if (additionalDictAttributes.containsKey(dictType)) {
+                    userHistoryDictionary.clearAndFlushDictionaryWithAdditionalAttributes(
+                            additionalDictAttributes.get(dictType));
+                }
             } else if (dictType.equals(Dictionary.TYPE_PERSONALIZATION)) {
                 final PersonalizationDictionary personalizationDictionary =
                         PersonalizationHelper.getPersonalizationDictionary(context, locale);
@@ -167,6 +173,10 @@
                 personalizationDictionary.reloadDictionaryIfRequired();
                 personalizationDictionary.waitAllTasksForTests();
                 setPersonalizationDictionary(personalizationDictionary);
+                if (additionalDictAttributes.containsKey(dictType)) {
+                    personalizationDictionary.clearAndFlushDictionaryWithAdditionalAttributes(
+                            additionalDictAttributes.get(dictType));
+                }
             } else if (dictType.equals(Dictionary.TYPE_USER)) {
                 final File file = dictionaryFiles.get(dictType);
                 final UserBinaryDictionary userDictionary = new UserBinaryDictionary(
diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index 44282a4..8ab1bb6 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -853,7 +853,7 @@
         }
         // This will set the punctuation suggestions if next word suggestion is off;
         // otherwise it will clear the suggestion strip.
-        setNeutralSuggestionStripInternal(false /* needsInputViewShown */);
+        setNeutralSuggestionStripInternal();
 
         mHandler.cancelUpdateSuggestionStrip();
         mHandler.cancelDoubleSpacePeriodTimer();
@@ -1018,23 +1018,18 @@
                 null /* rawSuggestions */, false /* typedWordValid */, false /* willAutoCorrect */,
                 false /* isObsoleteSuggestions */, false /* isPrediction */);
         // When in fullscreen mode, show completions generated by the application forcibly
-        setSuggestedWords(suggestedWords, true /* isSuggestionStripVisible */,
-                true /* needsInputViewShown */);
+        setSuggestedWords(suggestedWords, true /* isSuggestionStripVisible */);
         if (ProductionFlag.USES_DEVELOPMENT_ONLY_DIAGNOSTICS) {
             ResearchLogger.latinIME_onDisplayCompletions(applicationSpecifiedCompletions);
         }
     }
 
-    private void setSuggestionStripShownInternal(final boolean isSuggestionStripVisible,
-            final boolean needsInputViewShown) {
+    private void setSuggestionStripShownInternal(final boolean isSuggestionStripVisible) {
         // TODO: Modify this if we support suggestions with hard keyboard
         if (!onEvaluateInputViewShown() || !hasSuggestionStripView()) {
             return;
         }
-        final boolean inputViewShown = mKeyboardSwitcher.isShowingMainKeyboardOrEmojiPalettes();
-        final boolean shouldShowSuggestions = isSuggestionStripVisible
-                && (needsInputViewShown ? inputViewShown : true);
-        if (shouldShowSuggestions) {
+        if (isSuggestionStripVisible) {
             mSuggestionStripView.setVisibility(View.VISIBLE);
         } else {
             mSuggestionStripView.setVisibility(isFullscreenMode() ? View.GONE : View.INVISIBLE);
@@ -1321,8 +1316,7 @@
         // Nothing to do so far.
     }
 
-    // TODO[IL]: Define a clear interface for this
-    public boolean isSuggestionStripVisible() {
+    private boolean isSuggestionStripVisible() {
         if (!hasSuggestionStripView()) {
             return false;
         }
@@ -1346,7 +1340,6 @@
         return currentSettings.isSuggestionsRequested();
     }
 
-    @Override
     public boolean hasSuggestionStripView() {
         return null != mSuggestionStripView;
     }
@@ -1366,7 +1359,7 @@
 
     // TODO[IL]: Define a clear interface for this
     public void setSuggestedWords(final SuggestedWords suggestedWords,
-            final boolean isSuggestionStripVisible, final boolean needsInputViewShown) {
+            final boolean isSuggestionStripVisible) {
         mInputLogic.setSuggestedWords(suggestedWords);
         if (!hasSuggestionStripView()) {
             return;
@@ -1386,7 +1379,7 @@
                     SubtypeLocaleUtils.isRtlLanguage(mSubtypeSwitcher.getCurrentSubtype()));
         }
         mKeyboardSwitcher.onAutoCorrectionStateChanged(suggestedWords.mWillAutoCorrect);
-        setSuggestionStripShownInternal(isSuggestionStripVisible, needsInputViewShown);
+        setSuggestionStripShownInternal(isSuggestionStripVisible);
     }
 
     // TODO[IL]: Move this out of LatinIME.
@@ -1472,8 +1465,7 @@
             setNeutralSuggestionStrip();
         } else {
             mInputLogic.mWordComposer.setAutoCorrection(autoCorrection);
-            setSuggestedWords(
-                    suggestedWords, isSuggestionStripVisible(), true /* needsInputViewShown */);
+            setSuggestedWords(suggestedWords, isSuggestionStripVisible());
         }
         // Cache the auto-correction in accessibility code so we can speak it if the user
         // touches a key that will insert it.
@@ -1502,14 +1494,14 @@
     // punctuation suggestions (if it's disabled).
     @Override
     public void setNeutralSuggestionStrip() {
-        setNeutralSuggestionStripInternal(true /* needsInputViewShown */);
+        setNeutralSuggestionStripInternal();
     }
 
-    private void setNeutralSuggestionStripInternal(final boolean needsInputViewShown) {
+    private void setNeutralSuggestionStripInternal() {
         final SettingsValues currentSettings = mSettings.getCurrent();
         final SuggestedWords neutralSuggestions = currentSettings.mBigramPredictionEnabled
                 ? SuggestedWords.EMPTY : currentSettings.mSpacingAndPunctuations.mSuggestPuncList;
-        setSuggestedWords(neutralSuggestions, isSuggestionStripVisible(), needsInputViewShown);
+        setSuggestedWords(neutralSuggestions, isSuggestionStripVisible());
     }
 
     // TODO: Make this private
diff --git a/java/src/com/android/inputmethod/latin/makedict/DictionaryHeader.java b/java/src/com/android/inputmethod/latin/makedict/DictionaryHeader.java
index b99e281..ed9c396 100644
--- a/java/src/com/android/inputmethod/latin/makedict/DictionaryHeader.java
+++ b/java/src/com/android/inputmethod/latin/makedict/DictionaryHeader.java
@@ -38,6 +38,10 @@
     public static final String DICTIONARY_DATE_KEY = "date";
     public static final String HAS_HISTORICAL_INFO_KEY = "HAS_HISTORICAL_INFO";
     public static final String USES_FORGETTING_CURVE_KEY = "USES_FORGETTING_CURVE";
+    public static final String FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP_KEY =
+            "FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP";
+    public static final String FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID_KEY =
+            "FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID";
     public static final String ATTRIBUTE_VALUE_TRUE = "1";
 
     public DictionaryHeader(final int headerSize, final DictionaryOptions dictionaryOptions,
diff --git a/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java b/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
index d3734d6..8c358cd 100644
--- a/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
+++ b/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
@@ -50,6 +50,7 @@
     public final Locale mLocale;
 
     private final String mDictName;
+    private Map<String, String> mAdditionalAttributeMap = null;
 
     protected DecayingExpandableBinaryDictionaryBase(final Context context,
             final String dictName, final Locale locale, final String dictionaryType,
@@ -78,7 +79,10 @@
 
     @Override
     protected Map<String, String> getHeaderAttributeMap() {
-        HashMap<String, String> attributeMap = new HashMap<String, String>();
+        final Map<String, String> attributeMap = new HashMap<String, String>();
+        if (mAdditionalAttributeMap != null) {
+            attributeMap.putAll(mAdditionalAttributeMap);
+        }
         attributeMap.put(DictionaryHeader.USES_FORGETTING_CURVE_KEY,
                 DictionaryHeader.ATTRIBUTE_VALUE_TRUE);
         attributeMap.put(DictionaryHeader.HAS_HISTORICAL_INFO_KEY,
@@ -152,6 +156,13 @@
         asyncFlushBinaryDictionary();
     }
 
+    @UsedForTesting
+    public void clearAndFlushDictionaryWithAdditionalAttributes(
+            final Map<String, String> attributeMap) {
+        mAdditionalAttributeMap = attributeMap;
+        clearAndFlushDictionary();
+    }
+
     /* package */ void decayIfNeeded() {
         runGCIfRequired(false /* mindsBlockByGC */);
     }
diff --git a/java/src/com/android/inputmethod/latin/suggestions/SuggestionStripViewAccessor.java b/java/src/com/android/inputmethod/latin/suggestions/SuggestionStripViewAccessor.java
index 60f1c7a..5270845 100644
--- a/java/src/com/android/inputmethod/latin/suggestions/SuggestionStripViewAccessor.java
+++ b/java/src/com/android/inputmethod/latin/suggestions/SuggestionStripViewAccessor.java
@@ -22,7 +22,6 @@
  * An object that gives basic control of a suggestion strip and some info on it.
  */
 public interface SuggestionStripViewAccessor {
-    public boolean hasSuggestionStripView();
     public void showAddToDictionaryHint(final String word);
     public boolean isShowingAddToDictionaryHint();
     public void dismissAddToDictionaryHint();
diff --git a/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java b/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
index a1d6415..562ff9e 100644
--- a/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
+++ b/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
@@ -37,9 +37,9 @@
     // non-0. Thus, it's not meaningful to compare 10, 100, and so on.
     // TODO: Revise the logic in ForgettingCurveUtils in native code.
     private static final int UNIGRAM_PROBABILITY_FOR_VALID_WORD = 100;
-    private static final int UNIGRAM_PROBABILITY_FOR_OOV_WORD = 10;
-    private static final int BIGRAM_PROBABILITY_FOR_VALID_WORD = 0;
-    private static final int BIGRAM_PROBABILITY_FOR_OOV_WORD = 0;
+    private static final int UNIGRAM_PROBABILITY_FOR_OOV_WORD = Dictionary.NOT_A_PROBABILITY;
+    private static final int BIGRAM_PROBABILITY_FOR_VALID_WORD = 10;
+    private static final int BIGRAM_PROBABILITY_FOR_OOV_WORD = Dictionary.NOT_A_PROBABILITY;
 
     public final String mTargetWord;
     public final int[] mWord0;
diff --git a/native/jni/src/suggest/core/policy/dictionary_header_structure_policy.h b/native/jni/src/suggest/core/policy/dictionary_header_structure_policy.h
index 59748c8..a8dab9f 100644
--- a/native/jni/src/suggest/core/policy/dictionary_header_structure_policy.h
+++ b/native/jni/src/suggest/core/policy/dictionary_header_structure_policy.h
@@ -44,8 +44,6 @@
 
     virtual float getMultiWordCostMultiplier() const = 0;
 
-    virtual int getLastDecayedTime() const = 0;
-
     virtual void readHeaderValueOrQuestionMark(const char *const key, int *outValue,
             int outValueSize) const = 0;
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp
index cd22430..7f91667 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp
@@ -37,7 +37,8 @@
     if (outProbability) {
         if (bigramEntry.hasHistoricalInfo()) {
             *outProbability =
-                    ForgettingCurveUtils::decodeProbability(bigramEntry.getHistoricalInfo());
+                    ForgettingCurveUtils::decodeProbability(bigramEntry.getHistoricalInfo(),
+                            mHeaderPolicy);
         } else {
             *outProbability = bigramEntry.getProbability();
         }
@@ -160,7 +161,7 @@
             }
         } else if (bigramEntry.hasHistoricalInfo()) {
             const HistoricalInfo historicalInfo = ForgettingCurveUtils::createHistoricalInfoToSave(
-                    bigramEntry.getHistoricalInfo());
+                    bigramEntry.getHistoricalInfo(), mHeaderPolicy);
             if (ForgettingCurveUtils::needsToKeep(&historicalInfo)) {
                 const BigramEntry updatedBigramEntry =
                         bigramEntry.updateHistoricalInfoAndGetEntry(&historicalInfo);
@@ -230,7 +231,8 @@
     if (mHeaderPolicy->hasHistoricalInfoOfWords()) {
         const HistoricalInfo updatedHistoricalInfo =
                 ForgettingCurveUtils::createUpdatedHistoricalInfo(
-                        originalBigramEntry->getHistoricalInfo(), newProbability, timestamp);
+                        originalBigramEntry->getHistoricalInfo(), newProbability, timestamp,
+                        mHeaderPolicy);
         return originalBigramEntry->updateHistoricalInfoAndGetEntry(&updatedHistoricalInfo);
     } else {
         return originalBigramEntry->updateProbabilityAndGetEntry(newProbability);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
index 3ce57d9..2ac417b 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
@@ -18,7 +18,7 @@
 
 namespace latinime {
 
-// Note that these are corresponding definitions in Java side in FormatSpec.FileHeader.
+// Note that these are corresponding definitions in Java side in DictionaryHeader.
 const char *const HeaderPolicy::MULTIPLE_WORDS_DEMOTION_RATE_KEY = "MULTIPLE_WORDS_DEMOTION_RATE";
 const char *const HeaderPolicy::REQUIRES_GERMAN_UMLAUT_PROCESSING_KEY =
         "REQUIRES_GERMAN_UMLAUT_PROCESSING";
@@ -33,8 +33,15 @@
 // count.
 const char *const HeaderPolicy::HAS_HISTORICAL_INFO_KEY = "HAS_HISTORICAL_INFO";
 const char *const HeaderPolicy::LOCALE_KEY = "locale"; // match Java declaration
+const char *const HeaderPolicy::FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP_KEY =
+        "FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP";
+const char *const HeaderPolicy::FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID_KEY =
+        "FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID";
+
 const int HeaderPolicy::DEFAULT_MULTIPLE_WORDS_DEMOTION_RATE = 100;
 const float HeaderPolicy::MULTIPLE_WORD_COST_MULTIPLIER_SCALE = 100.0f;
+const int HeaderPolicy::DEFAULT_FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP = 4;
+const int HeaderPolicy::DEFAULT_FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID = 0;
 
 // Used for logging. Question mark is used to indicate that the key is not found.
 void HeaderPolicy::readHeaderValueOrQuestionMark(const char *const key, int *outValue,
diff --git a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
index fc34761..8fa7e16 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
@@ -52,7 +52,13 @@
               mExtendedRegionSize(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
                       EXTENDED_REGION_SIZE_KEY, 0 /* defaultValue */)),
               mHasHistoricalInfoOfWords(HeaderReadWriteUtils::readBoolAttributeValue(
-                      &mAttributeMap, HAS_HISTORICAL_INFO_KEY, false /* defaultValue */)) {}
+                      &mAttributeMap, HAS_HISTORICAL_INFO_KEY, false /* defaultValue */)),
+              mForgettingCurveOccurrencesToLevelUp(HeaderReadWriteUtils::readIntAttributeValue(
+                      &mAttributeMap, FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP_KEY,
+                      DEFAULT_FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP)),
+              mForgettingCurveProbabilityValuesTableId(HeaderReadWriteUtils::readIntAttributeValue(
+                      &mAttributeMap, FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID_KEY,
+                      DEFAULT_FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID)) {}
 
     // Constructs header information using an attribute map.
     HeaderPolicy(const FormatUtils::FORMAT_VERSION dictFormatVersion,
@@ -71,8 +77,13 @@
                       DATE_KEY, TimeKeeper::peekCurrentTime() /* defaultValue */)),
               mUnigramCount(0), mBigramCount(0), mExtendedRegionSize(0),
               mHasHistoricalInfoOfWords(HeaderReadWriteUtils::readBoolAttributeValue(
-                      &mAttributeMap, HAS_HISTORICAL_INFO_KEY, false /* defaultValue */)) {
-        }
+                      &mAttributeMap, HAS_HISTORICAL_INFO_KEY, false /* defaultValue */)),
+              mForgettingCurveOccurrencesToLevelUp(HeaderReadWriteUtils::readIntAttributeValue(
+                      &mAttributeMap, FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP_KEY,
+                      DEFAULT_FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP)),
+              mForgettingCurveProbabilityValuesTableId(HeaderReadWriteUtils::readIntAttributeValue(
+                      &mAttributeMap, FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID_KEY,
+                      DEFAULT_FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID)) {}
 
     // Temporary dummy header.
     HeaderPolicy()
@@ -80,7 +91,8 @@
               mAttributeMap(), mLocale(CharUtils::EMPTY_STRING), mMultiWordCostMultiplier(0.0f),
               mRequiresGermanUmlautProcessing(false), mIsDecayingDict(false),
               mDate(0), mLastDecayedTime(0), mUnigramCount(0), mBigramCount(0),
-              mExtendedRegionSize(0), mHasHistoricalInfoOfWords(false) {}
+              mExtendedRegionSize(0), mHasHistoricalInfoOfWords(false),
+              mForgettingCurveOccurrencesToLevelUp(0), mForgettingCurveProbabilityValuesTableId(0) {}
 
     ~HeaderPolicy() {}
 
@@ -159,6 +171,14 @@
         return &mAttributeMap;
     }
 
+    AK_FORCE_INLINE int getForgettingCurveOccurrencesToLevelUp() const {
+        return mForgettingCurveOccurrencesToLevelUp;
+    }
+
+    AK_FORCE_INLINE int getForgettingCurveProbabilityValuesTableId() const {
+        return mForgettingCurveProbabilityValuesTableId;
+    }
+
     void readHeaderValueOrQuestionMark(const char *const key,
             int *outValue, int outValueSize) const;
 
@@ -183,8 +203,12 @@
     static const char *const EXTENDED_REGION_SIZE_KEY;
     static const char *const HAS_HISTORICAL_INFO_KEY;
     static const char *const LOCALE_KEY;
+    static const char *const FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP_KEY;
+    static const char *const FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID_KEY;
     static const int DEFAULT_MULTIPLE_WORDS_DEMOTION_RATE;
     static const float MULTIPLE_WORD_COST_MULTIPLIER_SCALE;
+    static const int DEFAULT_FORGETTING_CURVE_OCCURRENCES_TO_LEVEL_UP;
+    static const int DEFAULT_FORGETTING_CURVE_PROBABILITY_VALUES_TABLE_ID;
 
     const FormatUtils::FORMAT_VERSION mDictFormatVersion;
     const HeaderReadWriteUtils::DictionaryFlags mDictionaryFlags;
@@ -200,6 +224,8 @@
     const int mBigramCount;
     const int mExtendedRegionSize;
     const bool mHasHistoricalInfoOfWords;
+    const int mForgettingCurveOccurrencesToLevelUp;
+    const int mForgettingCurveProbabilityValuesTableId;
 
     const std::vector<int> readLocale() const;
     float readMultipleWordCostMultiplier() const;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp
index cb9d450..279f5b3 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp
@@ -23,6 +23,13 @@
 const BigramEntry BigramDictContent::getBigramEntryAndAdvancePosition(
         int *const bigramEntryPos) const {
     const BufferWithExtendableBuffer *const bigramListBuffer = getContentBuffer();
+    if (*bigramEntryPos < 0 || *bigramEntryPos >=  bigramListBuffer->getTailPosition()) {
+        AKLOGE("Invalid bigram entry position. bigramEntryPos: %d, bufSize: %d",
+                *bigramEntryPos, bigramListBuffer->getTailPosition());
+        ASSERT(false);
+        return BigramEntry(false /* hasNext */, NOT_A_PROBABILITY,
+                Ver4DictConstants::NOT_A_TERMINAL_ID);
+    }
     const int bigramFlags = bigramListBuffer->readUintAndAdvancePosition(
             Ver4DictConstants::BIGRAM_FLAGS_FIELD_SIZE, bigramEntryPos);
     const bool hasNext = (bigramFlags & Ver4DictConstants::BIGRAM_HAS_NEXT_MASK) != 0;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
index 29972a4..64d7bc0 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
@@ -24,6 +24,19 @@
         int *const outCodePoint, int *const outCodePointCount, int *const outProbability,
         bool *const outhasNext, int *const shortcutEntryPos) const {
     const BufferWithExtendableBuffer *const shortcutListBuffer = getContentBuffer();
+    if (*shortcutEntryPos < 0 || *shortcutEntryPos >=  shortcutListBuffer->getTailPosition()) {
+        AKLOGE("Invalid shortcut entry position. shortcutEntryPos: %d, bufSize: %d",
+                *shortcutEntryPos, shortcutListBuffer->getTailPosition());
+        ASSERT(false);
+        if (outhasNext) {
+            *outhasNext = false;
+        }
+        if (outCodePointCount) {
+            *outCodePointCount = 0;
+        }
+        return;
+    }
+
     const int shortcutFlags = shortcutListBuffer->readUintAndAdvancePosition(
             Ver4DictConstants::SHORTCUT_FLAGS_FIELD_SIZE, shortcutEntryPos);
     if (outProbability) {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.cpp
index 17fc948..f149781 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.cpp
@@ -65,7 +65,7 @@
                 mProbabilityDictContent->getProbabilityEntry(terminalId);
         if (probabilityEntry.hasHistoricalInfo()) {
             probability = ForgettingCurveUtils::decodeProbability(
-                    probabilityEntry.getHistoricalInfo());
+                    probabilityEntry.getHistoricalInfo(), mHeaderPolicy);
         } else {
             probability = probabilityEntry.getProbability();
         }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.h
index 9d93245..1db9ea0 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.h
@@ -26,6 +26,7 @@
 namespace latinime {
 
 class BufferWithExtendableBuffer;
+class HeaderPolicy;
 class ProbabilityDictContent;
 
 /*
@@ -35,8 +36,10 @@
 class Ver4PatriciaTrieNodeReader : public PtNodeReader {
  public:
     Ver4PatriciaTrieNodeReader(const BufferWithExtendableBuffer *const buffer,
-            const ProbabilityDictContent *const probabilityDictContent)
-            : mBuffer(buffer), mProbabilityDictContent(probabilityDictContent) {}
+            const ProbabilityDictContent *const probabilityDictContent,
+            const HeaderPolicy *const headerPolicy)
+            : mBuffer(buffer), mProbabilityDictContent(probabilityDictContent),
+              mHeaderPolicy(headerPolicy) {}
 
     ~Ver4PatriciaTrieNodeReader() {}
 
@@ -50,6 +53,7 @@
 
     const BufferWithExtendableBuffer *const mBuffer;
     const ProbabilityDictContent *const mProbabilityDictContent;
+    const HeaderPolicy *const mHeaderPolicy;
 
     const PtNodeParams fetchPtNodeInfoFromBufferAndProcessMovedPtNode(const int ptNodePos,
             const int siblingNodePos) const;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp
index 32576cf..13ae9d9 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp
@@ -159,7 +159,7 @@
                     toBeUpdatedPtNodeParams->getTerminalId());
     if (originalProbabilityEntry.hasHistoricalInfo()) {
         const HistoricalInfo historicalInfo = ForgettingCurveUtils::createHistoricalInfoToSave(
-                originalProbabilityEntry.getHistoricalInfo());
+                originalProbabilityEntry.getHistoricalInfo(), mHeaderPolicy);
         const ProbabilityEntry probabilityEntry =
                 originalProbabilityEntry.createEntryWithUpdatedHistoricalInfo(&historicalInfo);
         if (!mBuffers->getMutableProbabilityDictContent()->setProbabilityEntry(
@@ -382,10 +382,11 @@
         const ProbabilityEntry *const originalProbabilityEntry, const int newProbability,
         const int timestamp) const {
     // TODO: Consolidate historical info and probability.
-    if (mBuffers->getHeaderPolicy()->hasHistoricalInfoOfWords()) {
+    if (mHeaderPolicy->hasHistoricalInfoOfWords()) {
         const HistoricalInfo updatedHistoricalInfo =
                 ForgettingCurveUtils::createUpdatedHistoricalInfo(
-                        originalProbabilityEntry->getHistoricalInfo(), newProbability, timestamp);
+                        originalProbabilityEntry->getHistoricalInfo(), newProbability, timestamp,
+                        mHeaderPolicy);
         return originalProbabilityEntry->createEntryWithUpdatedHistoricalInfo(
                 &updatedHistoricalInfo);
     } else {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h
index 66845bb..f01b3af 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h
@@ -28,6 +28,7 @@
 namespace latinime {
 
 class BufferWithExtendableBuffer;
+class HeaderPolicy;
 class Ver4BigramListPolicy;
 class Ver4DictBuffers;
 class Ver4PatriciaTrieNodeReader;
@@ -40,10 +41,11 @@
 class Ver4PatriciaTrieNodeWriter : public PtNodeWriter {
  public:
     Ver4PatriciaTrieNodeWriter(BufferWithExtendableBuffer *const trieBuffer,
-            Ver4DictBuffers *const buffers, const PtNodeReader *const ptNodeReader,
+            Ver4DictBuffers *const buffers, const HeaderPolicy *const headerPolicy,
+            const PtNodeReader *const ptNodeReader,
             const PtNodeArrayReader *const ptNodeArrayReader,
             Ver4BigramListPolicy *const bigramPolicy, Ver4ShortcutListPolicy *const shortcutPolicy)
-            : mTrieBuffer(trieBuffer), mBuffers(buffers),
+            : mTrieBuffer(trieBuffer), mBuffers(buffers), mHeaderPolicy(headerPolicy),
               mReadingHelper(ptNodeReader, ptNodeArrayReader), mBigramPolicy(bigramPolicy),
               mShortcutPolicy(shortcutPolicy) {}
 
@@ -116,6 +118,7 @@
 
     BufferWithExtendableBuffer *const mTrieBuffer;
     Ver4DictBuffers *const mBuffers;
+    const HeaderPolicy *const mHeaderPolicy;
     DynamicPtReadingHelper mReadingHelper;
     Ver4BigramListPolicy *const mBigramPolicy;
     Ver4ShortcutListPolicy *const mShortcutPolicy;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
index b5d80be..197250f 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
@@ -382,7 +382,8 @@
                     bigramWord1CodePoints + codePointCount);
             const HistoricalInfo *const historicalInfo = bigramEntry.getHistoricalInfo();
             const int probability = bigramEntry.hasHistoricalInfo() ?
-                    ForgettingCurveUtils::decodeProbability(bigramEntry.getHistoricalInfo()) :
+                    ForgettingCurveUtils::decodeProbability(
+                            bigramEntry.getHistoricalInfo(), mHeaderPolicy) :
                     bigramEntry.getProbability();
             bigrams.push_back(WordProperty::BigramProperty(&word1, probability,
                     historicalInfo->getTimeStamp(), historicalInfo->getLevel(),
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
index 7796e2d..639c153 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
@@ -47,10 +47,10 @@
                       mBuffers.get()->getTerminalPositionLookupTable(), mHeaderPolicy),
               mShortcutPolicy(mBuffers.get()->getMutableShortcutDictContent(),
                       mBuffers.get()->getTerminalPositionLookupTable()),
-              mNodeReader(mDictBuffer, mBuffers.get()->getProbabilityDictContent()),
+              mNodeReader(mDictBuffer, mBuffers.get()->getProbabilityDictContent(), mHeaderPolicy),
               mPtNodeArrayReader(mDictBuffer),
-              mNodeWriter(mDictBuffer, mBuffers.get(), &mNodeReader, &mPtNodeArrayReader,
-                      &mBigramPolicy, &mShortcutPolicy),
+              mNodeWriter(mDictBuffer, mBuffers.get(), mHeaderPolicy, &mNodeReader,
+                      &mPtNodeArrayReader, &mBigramPolicy, &mShortcutPolicy),
               mUpdatingHelper(mDictBuffer, &mNodeReader, &mNodeWriter),
               mWritingHelper(mBuffers.get()),
               mUnigramCount(mHeaderPolicy->getUnigramCount()),
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
index 93053c3..2da2950 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
@@ -74,14 +74,15 @@
         const HeaderPolicy *const headerPolicy, Ver4DictBuffers *const buffersToWrite,
         int *const outUnigramCount, int *const outBigramCount) {
     Ver4PatriciaTrieNodeReader ptNodeReader(mBuffers->getTrieBuffer(),
-            mBuffers->getProbabilityDictContent());
+            mBuffers->getProbabilityDictContent(), headerPolicy);
     Ver4PtNodeArrayReader ptNodeArrayReader(mBuffers->getTrieBuffer());
     Ver4BigramListPolicy bigramPolicy(mBuffers->getMutableBigramDictContent(),
             mBuffers->getTerminalPositionLookupTable(), headerPolicy);
     Ver4ShortcutListPolicy shortcutPolicy(mBuffers->getMutableShortcutDictContent(),
             mBuffers->getTerminalPositionLookupTable());
     Ver4PatriciaTrieNodeWriter ptNodeWriter(mBuffers->getWritableTrieBuffer(),
-            mBuffers, &ptNodeReader, &ptNodeArrayReader, &bigramPolicy, &shortcutPolicy);
+            mBuffers, headerPolicy, &ptNodeReader, &ptNodeArrayReader, &bigramPolicy,
+            &shortcutPolicy);
 
     DynamicPtReadingHelper readingHelper(&ptNodeReader, &ptNodeArrayReader);
     readingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
@@ -126,7 +127,8 @@
     PtNodeWriter::DictPositionRelocationMap dictPositionRelocationMap;
     readingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
     Ver4PatriciaTrieNodeWriter ptNodeWriterForNewBuffers(buffersToWrite->getWritableTrieBuffer(),
-            buffersToWrite, &ptNodeReader, &ptNodeArrayReader, &bigramPolicy, &shortcutPolicy);
+            buffersToWrite, headerPolicy, &ptNodeReader, &ptNodeArrayReader, &bigramPolicy,
+            &shortcutPolicy);
     DynamicPtGcEventListeners::TraversePolicyToPlaceAndWriteValidPtNodesToBuffer
             traversePolicyToPlaceAndWriteValidPtNodesToBuffer(&ptNodeWriterForNewBuffers,
                     buffersToWrite->getWritableTrieBuffer(), &dictPositionRelocationMap);
@@ -137,14 +139,14 @@
 
     // Create policy instances for the GCed dictionary.
     Ver4PatriciaTrieNodeReader newPtNodeReader(buffersToWrite->getTrieBuffer(),
-            buffersToWrite->getProbabilityDictContent());
+            buffersToWrite->getProbabilityDictContent(), headerPolicy);
     Ver4PtNodeArrayReader newPtNodeArrayreader(buffersToWrite->getTrieBuffer());
     Ver4BigramListPolicy newBigramPolicy(buffersToWrite->getMutableBigramDictContent(),
             buffersToWrite->getTerminalPositionLookupTable(), headerPolicy);
     Ver4ShortcutListPolicy newShortcutPolicy(buffersToWrite->getMutableShortcutDictContent(),
             buffersToWrite->getTerminalPositionLookupTable());
     Ver4PatriciaTrieNodeWriter newPtNodeWriter(buffersToWrite->getWritableTrieBuffer(),
-            buffersToWrite, &newPtNodeReader, &newPtNodeArrayreader, &newBigramPolicy,
+            buffersToWrite, headerPolicy, &newPtNodeReader, &newPtNodeArrayreader, &newBigramPolicy,
             &newShortcutPolicy);
     // Re-assign terminal IDs for valid terminal PtNodes.
     TerminalPositionLookupTable::TerminalIdMap terminalIdMap;
@@ -202,8 +204,9 @@
         const ProbabilityEntry probabilityEntry =
                 mBuffers->getProbabilityDictContent()->getProbabilityEntry(i);
         const int probability = probabilityEntry.hasHistoricalInfo() ?
-                ForgettingCurveUtils::decodeProbability(probabilityEntry.getHistoricalInfo()) :
-                        probabilityEntry.getProbability();
+                ForgettingCurveUtils::decodeProbability(
+                        probabilityEntry.getHistoricalInfo(), mBuffers->getHeaderPolicy()) :
+                probabilityEntry.getProbability();
         priorityQueue.push(DictProbability(terminalPos, probability,
                 probabilityEntry.getHistoricalInfo()->getTimeStamp()));
     }
@@ -245,8 +248,9 @@
                 continue;
             }
             const int probability = bigramEntry.hasHistoricalInfo() ?
-                    ForgettingCurveUtils::decodeProbability(bigramEntry.getHistoricalInfo()) :
-                            bigramEntry.getProbability();
+                    ForgettingCurveUtils::decodeProbability(
+                            bigramEntry.getHistoricalInfo(), mBuffers->getHeaderPolicy()) :
+                    bigramEntry.getProbability();
             priorityQueue.push(DictProbability(entryPos, probability,
                     bigramEntry.getHistoricalInfo()->getTimeStamp()));
         }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.cpp
index d58d259..51b0eb2 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.cpp
@@ -19,7 +19,7 @@
 #include <cmath>
 #include <stdlib.h>
 
-#include "suggest/core/policy/dictionary_header_structure_policy.h"
+#include "suggest/policyimpl/dictionary/header/header_policy.h"
 #include "suggest/policyimpl/dictionary/utils/probability_utils.h"
 #include "utils/time_keeper.h"
 
@@ -30,11 +30,10 @@
 const int ForgettingCurveUtils::MAX_BIGRAM_COUNT = 12000;
 const int ForgettingCurveUtils::MAX_BIGRAM_COUNT_AFTER_GC = 10000;
 
-const int ForgettingCurveUtils::MAX_COMPUTED_PROBABILITY = 127;
+const int ForgettingCurveUtils::MULTIPLIER_TWO_IN_PROBABILITY_SCALE = 8;
 const int ForgettingCurveUtils::DECAY_INTERVAL_SECONDS = 2 * 60 * 60;
 
 const int ForgettingCurveUtils::MAX_LEVEL = 3;
-const int ForgettingCurveUtils::MAX_COUNT = 3;
 const int ForgettingCurveUtils::MIN_VALID_LEVEL = 1;
 const int ForgettingCurveUtils::TIME_STEP_DURATION_IN_SECONDS = 6 * 60 * 60;
 const int ForgettingCurveUtils::MAX_ELAPSED_TIME_STEP_COUNT = 15;
@@ -45,7 +44,7 @@
 // TODO: Revise the logic to decide the initial probability depending on the given probability.
 /* static */ const HistoricalInfo ForgettingCurveUtils::createUpdatedHistoricalInfo(
         const HistoricalInfo *const originalHistoricalInfo,
-        const int newProbability, const int timestamp) {
+        const int newProbability, const int timestamp, const HeaderPolicy *const headerPolicy) {
     if (newProbability != NOT_A_PROBABILITY && originalHistoricalInfo->getLevel() == 0) {
         return HistoricalInfo(timestamp, MIN_VALID_LEVEL /* level */, 0 /* count */);
     } else if (!originalHistoricalInfo->isValid()) {
@@ -53,7 +52,7 @@
         return HistoricalInfo(timestamp, 0 /* level */, 1 /* count */);
     } else {
         const int updatedCount = originalHistoricalInfo->getCount() + 1;
-        if (updatedCount > MAX_COUNT) {
+        if (updatedCount >= headerPolicy->getForgettingCurveOccurrencesToLevelUp()) {
             // The count exceeds the max value the level can be incremented.
             if (originalHistoricalInfo->getLevel() >= MAX_LEVEL) {
                 // The level is already max.
@@ -71,9 +70,10 @@
 }
 
 /* static */ int ForgettingCurveUtils::decodeProbability(
-        const HistoricalInfo *const historicalInfo) {
+        const HistoricalInfo *const historicalInfo, const HeaderPolicy *const headerPolicy) {
     const int elapsedTimeStepCount = getElapsedTimeStepCount(historicalInfo->getTimeStamp());
-    return sProbabilityTable.getProbability(historicalInfo->getLevel(),
+    return sProbabilityTable.getProbability(
+            headerPolicy->getForgettingCurveProbabilityValuesTableId(), historicalInfo->getLevel(),
             min(max(elapsedTimeStepCount, 0), MAX_ELAPSED_TIME_STEP_COUNT));
 }
 
@@ -82,9 +82,11 @@
     if (unigramProbability == NOT_A_PROBABILITY) {
         return NOT_A_PROBABILITY;
     } else if (bigramProbability == NOT_A_PROBABILITY) {
-        return min(backoff(unigramProbability), MAX_COMPUTED_PROBABILITY);
+        return min(backoff(unigramProbability), MAX_PROBABILITY);
     } else {
-        return min(max(unigramProbability, bigramProbability), MAX_COMPUTED_PROBABILITY);
+        // TODO: Investigate better way to handle bigram probability.
+        return min(max(unigramProbability, bigramProbability + MULTIPLIER_TWO_IN_PROBABILITY_SCALE),
+                MAX_PROBABILITY);
     }
 }
 
@@ -95,7 +97,8 @@
 }
 
 /* static */ const HistoricalInfo ForgettingCurveUtils::createHistoricalInfoToSave(
-        const HistoricalInfo *const originalHistoricalInfo) {
+        const HistoricalInfo *const originalHistoricalInfo,
+        const HeaderPolicy *const headerPolicy) {
     if (originalHistoricalInfo->getTimeStamp() == NOT_A_TIMESTAMP) {
         return HistoricalInfo();
     }
@@ -115,8 +118,7 @@
 }
 
 /* static */ bool ForgettingCurveUtils::needsToDecay(const bool mindsBlockByDecay,
-        const int unigramCount, const int bigramCount,
-        const DictionaryHeaderStructurePolicy *const headerPolicy) {
+        const int unigramCount, const int bigramCount, const HeaderPolicy *const headerPolicy) {
     if (unigramCount >= ForgettingCurveUtils::MAX_UNIGRAM_COUNT) {
         // Unigram count exceeds the limit.
         return true;
@@ -137,37 +139,69 @@
 
 // See comments in ProbabilityUtils::backoff().
 /* static */ int ForgettingCurveUtils::backoff(const int unigramProbability) {
-    if (unigramProbability == NOT_A_PROBABILITY) {
-        return NOT_A_PROBABILITY;
-    } else {
-        return max(unigramProbability - 8, 0);
-    }
+    // See TODO comments in ForgettingCurveUtils::getProbability().
+    return unigramProbability;
 }
 
 /* static */ int ForgettingCurveUtils::getElapsedTimeStepCount(const int timestamp) {
     return (TimeKeeper::peekCurrentTime() - timestamp) / TIME_STEP_DURATION_IN_SECONDS;
 }
 
-ForgettingCurveUtils::ProbabilityTable::ProbabilityTable() : mTable() {
-    mTable.resize(MAX_LEVEL + 1);
-    for (int level = 0; level <= MAX_LEVEL; ++level) {
-        mTable[level].resize(MAX_ELAPSED_TIME_STEP_COUNT + 1);
-        const float initialProbability =
-                static_cast<float>(MAX_COMPUTED_PROBABILITY / (1 << (MAX_LEVEL - level)));
-        for (int timeStepCount = 0; timeStepCount <= MAX_ELAPSED_TIME_STEP_COUNT; ++timeStepCount) {
-            if (level == 0) {
-                mTable[level][timeStepCount] = NOT_A_PROBABILITY;
-                continue;
+const int ForgettingCurveUtils::ProbabilityTable::PROBABILITY_TABLE_COUNT = 4;
+const int ForgettingCurveUtils::ProbabilityTable::WEAK_PROBABILITY_TABLE_ID = 0;
+const int ForgettingCurveUtils::ProbabilityTable::MODEST_PROBABILITY_TABLE_ID = 1;
+const int ForgettingCurveUtils::ProbabilityTable::STRONG_PROBABILITY_TABLE_ID = 2;
+const int ForgettingCurveUtils::ProbabilityTable::AGGRESSIVE_PROBABILITY_TABLE_ID = 3;
+const int ForgettingCurveUtils::ProbabilityTable::WEAK_MAX_PROBABILITY = 127;
+const int ForgettingCurveUtils::ProbabilityTable::MODEST_BASE_PROBABILITY = 32;
+const int ForgettingCurveUtils::ProbabilityTable::STRONG_BASE_PROBABILITY = 35;
+const int ForgettingCurveUtils::ProbabilityTable::AGGRESSIVE_BASE_PROBABILITY = 40;
+
+
+ForgettingCurveUtils::ProbabilityTable::ProbabilityTable() : mTables() {
+    mTables.resize(PROBABILITY_TABLE_COUNT);
+    for (int tableId = 0; tableId < PROBABILITY_TABLE_COUNT; ++tableId) {
+        mTables[tableId].resize(MAX_LEVEL + 1);
+        for (int level = 0; level <= MAX_LEVEL; ++level) {
+            mTables[tableId][level].resize(MAX_ELAPSED_TIME_STEP_COUNT + 1);
+            const float initialProbability = getBaseProbabilityForLevel(tableId, level);
+            const float endProbability = getBaseProbabilityForLevel(tableId, level - 1);
+            for (int timeStepCount = 0; timeStepCount <= MAX_ELAPSED_TIME_STEP_COUNT;
+                    ++timeStepCount) {
+                if (level == 0) {
+                    mTables[tableId][level][timeStepCount] = NOT_A_PROBABILITY;
+                    continue;
+                }
+                const int elapsedTime = timeStepCount * TIME_STEP_DURATION_IN_SECONDS;
+                const float probability = initialProbability
+                        * powf(initialProbability / endProbability,
+                                -1.0f * static_cast<float>(elapsedTime)
+                                        / static_cast<float>(TIME_STEP_DURATION_IN_SECONDS
+                                                * (MAX_ELAPSED_TIME_STEP_COUNT + 1)));
+                mTables[tableId][level][timeStepCount] =
+                        min(max(static_cast<int>(probability), 1), MAX_PROBABILITY);
             }
-            const int elapsedTime = timeStepCount * TIME_STEP_DURATION_IN_SECONDS;
-            const float probability = initialProbability
-                    * powf(2.0f, -1.0f * static_cast<float>(elapsedTime)
-                            / static_cast<float>(TIME_STEP_DURATION_IN_SECONDS
-                                    * (MAX_ELAPSED_TIME_STEP_COUNT + 1)));
-            mTable[level][timeStepCount] =
-                    min(max(static_cast<int>(probability), 1), MAX_COMPUTED_PROBABILITY);
         }
     }
 }
 
+/* static */ int ForgettingCurveUtils::ProbabilityTable::getBaseProbabilityForLevel(
+        const int tableId, const int level) {
+    if (tableId == WEAK_PROBABILITY_TABLE_ID) {
+        // Max probability is 127.
+        return static_cast<float>(WEAK_MAX_PROBABILITY / (1 << (MAX_LEVEL - level)));
+    } else if (tableId == MODEST_PROBABILITY_TABLE_ID) {
+        // Max probability is 128.
+        return static_cast<float>(MODEST_BASE_PROBABILITY * (level + 1));
+    } else if (tableId == STRONG_PROBABILITY_TABLE_ID) {
+        // Max probability is 140.
+        return static_cast<float>(STRONG_BASE_PROBABILITY * (level + 1));
+    } else if (tableId == AGGRESSIVE_PROBABILITY_TABLE_ID) {
+        // Max probability is 160.
+        return static_cast<float>(AGGRESSIVE_BASE_PROBABILITY * (level + 1));
+    } else {
+        return NOT_A_PROBABILITY;
+    }
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h b/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
index b373534..1a285e5 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
@@ -24,7 +24,7 @@
 
 namespace latinime {
 
-class DictionaryHeaderStructurePolicy;
+class HeaderPolicy;
 
 class ForgettingCurveUtils {
  public:
@@ -35,12 +35,14 @@
 
     static const HistoricalInfo createUpdatedHistoricalInfo(
             const HistoricalInfo *const originalHistoricalInfo, const int newProbability,
-            const int timestamp);
+            const int timestamp, const HeaderPolicy *const headerPolicy);
 
     static const HistoricalInfo createHistoricalInfoToSave(
-            const HistoricalInfo *const originalHistoricalInfo);
+            const HistoricalInfo *const originalHistoricalInfo,
+            const HeaderPolicy *const headerPolicy);
 
-    static int decodeProbability(const HistoricalInfo *const historicalInfo);
+    static int decodeProbability(const HistoricalInfo *const historicalInfo,
+            const HeaderPolicy *const headerPolicy);
 
     static int getProbability(const int encodedUnigramProbability,
             const int encodedBigramProbability);
@@ -48,7 +50,7 @@
     static bool needsToKeep(const HistoricalInfo *const historicalInfo);
 
     static bool needsToDecay(const bool mindsBlockByDecay, const int unigramCount,
-            const int bigramCount, const DictionaryHeaderStructurePolicy *const headerPolicy);
+            const int bigramCount, const HeaderPolicy *const headerPolicy);
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(ForgettingCurveUtils);
@@ -57,21 +59,34 @@
      public:
         ProbabilityTable();
 
-        int getProbability(const int level, const int elapsedTimeStepCount) const {
-            return mTable[level][elapsedTimeStepCount];
+        int getProbability(const int tableId, const int level,
+                const int elapsedTimeStepCount) const {
+            return mTables[tableId][level][elapsedTimeStepCount];
         }
 
      private:
         DISALLOW_COPY_AND_ASSIGN(ProbabilityTable);
 
-        std::vector<std::vector<int> > mTable;
+        static const int PROBABILITY_TABLE_COUNT;
+        static const int WEAK_PROBABILITY_TABLE_ID;
+        static const int MODEST_PROBABILITY_TABLE_ID;
+        static const int STRONG_PROBABILITY_TABLE_ID;
+        static const int AGGRESSIVE_PROBABILITY_TABLE_ID;
+
+        static const int WEAK_MAX_PROBABILITY;
+        static const int MODEST_BASE_PROBABILITY;
+        static const int STRONG_BASE_PROBABILITY;
+        static const int AGGRESSIVE_BASE_PROBABILITY;
+
+        std::vector<std::vector<std::vector<int> > > mTables;
+
+        static int getBaseProbabilityForLevel(const int tableId, const int level);
     };
 
-    static const int MAX_COMPUTED_PROBABILITY;
+    static const int MULTIPLIER_TWO_IN_PROBABILITY_SCALE;
     static const int DECAY_INTERVAL_SECONDS;
 
     static const int MAX_LEVEL;
-    static const int MAX_COUNT;
     static const int MIN_VALID_LEVEL;
     static const int TIME_STEP_DURATION_IN_SECONDS;
     static const int MAX_ELAPSED_TIME_STEP_COUNT;
diff --git a/tests/src/com/android/inputmethod/keyboard/internal/KeyboardTextsSetTests.java b/tests/src/com/android/inputmethod/keyboard/internal/KeyboardTextsSetTests.java
new file mode 100644
index 0000000..17d7687
--- /dev/null
+++ b/tests/src/com/android/inputmethod/keyboard/internal/KeyboardTextsSetTests.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.keyboard.internal;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.SmallTest;
+import android.view.inputmethod.InputMethodInfo;
+import android.view.inputmethod.InputMethodSubtype;
+
+import com.android.inputmethod.latin.RichInputMethodManager;
+import com.android.inputmethod.latin.utils.CollectionUtils;
+import com.android.inputmethod.latin.utils.RunInLocale;
+import com.android.inputmethod.latin.utils.SubtypeLocaleUtils;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Locale;
+
+@SmallTest
+public final class KeyboardTextsSetTests extends AndroidTestCase {
+    // All input method subtypes of LatinIME.
+    private List<InputMethodSubtype> mAllSubtypesList;
+
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+        RichInputMethodManager.init(getContext());
+        final RichInputMethodManager richImm = RichInputMethodManager.getInstance();
+
+        final ArrayList<InputMethodSubtype> allSubtypesList = CollectionUtils.newArrayList();
+        final InputMethodInfo imi = richImm.getInputMethodInfoOfThisIme();
+        final int subtypeCount = imi.getSubtypeCount();
+        for (int index = 0; index < subtypeCount; index++) {
+            final InputMethodSubtype subtype = imi.getSubtypeAt(index);
+            allSubtypesList.add(subtype);
+        }
+        mAllSubtypesList = Collections.unmodifiableList(allSubtypesList);
+    }
+
+    // Test that the text {@link KeyboardTextsSet#SWITCH_TO_ALPHA_KEY_LABEL} exists for all
+    // subtypes. The text is needed to implement Emoji Keyboard, see
+    // {@link KeyboardSwitcher#setEmojiKeyboard()}.
+    public void testSwitchToAlphaKeyLabel() {
+        final KeyboardTextsSet textsSet = new KeyboardTextsSet();
+        for (final InputMethodSubtype subtype : mAllSubtypesList) {
+            final Locale locale = SubtypeLocaleUtils.getSubtypeLocale(subtype);
+            textsSet.setLocale(locale);
+            final String switchToAlphaKeyLabel = textsSet.getText(
+                    KeyboardTextsSet.SWITCH_TO_ALPHA_KEY_LABEL);
+            assertNotNull("Switch to alpha key label of " + locale, switchToAlphaKeyLabel);
+            assertFalse("Switch to alpha key label of " + locale, switchToAlphaKeyLabel.isEmpty());
+        }
+    }
+
+    private static final String[] TEXT_NAMES_FROM_RESOURCE = {
+        // Labels for action.
+        "label_go_key",
+        "label_send_key",
+        "label_next_key",
+        "label_done_key",
+        "label_previous_key",
+        // Other labels.
+        "label_pause_key",
+        "label_wait_key",
+    };
+
+    // Test that the text from resources are correctly loaded for all subtypes.
+    public void testTextFromResources() {
+        final Context context = getContext();
+        final KeyboardTextsSet textsSet = new KeyboardTextsSet();
+        for (final InputMethodSubtype subtype : mAllSubtypesList) {
+            final Locale locale = SubtypeLocaleUtils.getSubtypeLocale(subtype);
+            textsSet.setLocale(locale);
+            final RunInLocale<Void> job = new RunInLocale<Void>() {
+                @Override
+                protected Void job(final Resources res) {
+                    textsSet.loadStringResources(context);
+                    return null;
+                }
+            };
+            job.runInLocale(context.getResources(), locale);
+            for (final String name : TEXT_NAMES_FROM_RESOURCE) {
+                final String text = textsSet.getText(name);
+                assertNotNull(name + " of " + locale, text);
+                assertFalse(name + " of " + locale, text.isEmpty());
+            }
+        }
+    }
+}