diff --git a/neuralnetworks/1.0/vts/functional/BasicTests.cpp b/neuralnetworks/1.0/vts/functional/BasicTests.cpp
index cc44c9e..bda43b1 100644
--- a/neuralnetworks/1.0/vts/functional/BasicTests.cpp
+++ b/neuralnetworks/1.0/vts/functional/BasicTests.cpp
@@ -18,8 +18,12 @@
 
 #include "VtsHalNeuralnetworks.h"
 
+#include "1.0/Callbacks.h"
+
 namespace android::hardware::neuralnetworks::V1_0::vts::functional {
 
+using implementation::PreparedModelCallback;
+
 // create device test
 TEST_P(NeuralnetworksHidlTest, CreateDevice) {}
 
@@ -43,4 +47,136 @@
     EXPECT_TRUE(ret.isOk());
 }
 
+// detect cycle
+TEST_P(NeuralnetworksHidlTest, CycleTest) {
+    // opnd0 = TENSOR_FLOAT32            // model input
+    // opnd1 = TENSOR_FLOAT32            // model input
+    // opnd2 = INT32                     // model input
+    // opnd3 = ADD(opnd0, opnd4, opnd2)
+    // opnd4 = ADD(opnd1, opnd3, opnd2)
+    // opnd5 = ADD(opnd4, opnd0, opnd2)  // model output
+    //
+    //            +-----+
+    //            |     |
+    //            v     |
+    // 3 = ADD(0, 4, 2) |
+    // |                |
+    // +----------+     |
+    //            |     |
+    //            v     |
+    // 4 = ADD(1, 3, 2) |
+    // |                |
+    // +----------------+
+    // |
+    // |
+    // +-------+
+    //         |
+    //         v
+    // 5 = ADD(4, 0, 2)
+
+    const std::vector<Operand> operands = {
+            {
+                    // operands[0]
+                    .type = OperandType::TENSOR_FLOAT32,
+                    .dimensions = {1},
+                    .numberOfConsumers = 2,
+                    .scale = 0.0f,
+                    .zeroPoint = 0,
+                    .lifetime = OperandLifeTime::MODEL_INPUT,
+                    .location = {.poolIndex = 0, .offset = 0, .length = 0},
+            },
+            {
+                    // operands[1]
+                    .type = OperandType::TENSOR_FLOAT32,
+                    .dimensions = {1},
+                    .numberOfConsumers = 1,
+                    .scale = 0.0f,
+                    .zeroPoint = 0,
+                    .lifetime = OperandLifeTime::MODEL_INPUT,
+                    .location = {.poolIndex = 0, .offset = 0, .length = 0},
+            },
+            {
+                    // operands[2]
+                    .type = OperandType::INT32,
+                    .dimensions = {},
+                    .numberOfConsumers = 3,
+                    .scale = 0.0f,
+                    .zeroPoint = 0,
+                    .lifetime = OperandLifeTime::MODEL_INPUT,
+                    .location = {.poolIndex = 0, .offset = 0, .length = 0},
+            },
+            {
+                    // operands[3]
+                    .type = OperandType::TENSOR_FLOAT32,
+                    .dimensions = {1},
+                    .numberOfConsumers = 1,
+                    .scale = 0.0f,
+                    .zeroPoint = 0,
+                    .lifetime = OperandLifeTime::TEMPORARY_VARIABLE,
+                    .location = {.poolIndex = 0, .offset = 0, .length = 0},
+            },
+            {
+                    // operands[4]
+                    .type = OperandType::TENSOR_FLOAT32,
+                    .dimensions = {1},
+                    .numberOfConsumers = 2,
+                    .scale = 0.0f,
+                    .zeroPoint = 0,
+                    .lifetime = OperandLifeTime::TEMPORARY_VARIABLE,
+                    .location = {.poolIndex = 0, .offset = 0, .length = 0},
+            },
+            {
+                    // operands[5]
+                    .type = OperandType::TENSOR_FLOAT32,
+                    .dimensions = {1},
+                    .numberOfConsumers = 0,
+                    .scale = 0.0f,
+                    .zeroPoint = 0,
+                    .lifetime = OperandLifeTime::MODEL_OUTPUT,
+                    .location = {.poolIndex = 0, .offset = 0, .length = 0},
+            },
+    };
+
+    const std::vector<Operation> operations = {
+            {.type = OperationType::ADD, .inputs = {0, 4, 2}, .outputs = {3}},
+            {.type = OperationType::ADD, .inputs = {1, 3, 2}, .outputs = {4}},
+            {.type = OperationType::ADD, .inputs = {4, 0, 2}, .outputs = {5}},
+    };
+
+    const Model model = {
+            .operands = operands,
+            .operations = operations,
+            .inputIndexes = {0, 1, 2},
+            .outputIndexes = {5},
+            .operandValues = {},
+            .pools = {},
+    };
+
+    // ensure that getSupportedOperations() checks model validity
+    ErrorStatus supportedOpsErrorStatus = ErrorStatus::GENERAL_FAILURE;
+    Return<void> supportedOpsReturn = kDevice->getSupportedOperations(
+            model, [&model, &supportedOpsErrorStatus](ErrorStatus status,
+                                                      const hidl_vec<bool>& supported) {
+                supportedOpsErrorStatus = status;
+                if (status == ErrorStatus::NONE) {
+                    ASSERT_EQ(supported.size(), model.operations.size());
+                }
+            });
+    ASSERT_TRUE(supportedOpsReturn.isOk());
+    ASSERT_EQ(supportedOpsErrorStatus, ErrorStatus::INVALID_ARGUMENT);
+
+    // ensure that prepareModel() checks model validity
+    sp<PreparedModelCallback> preparedModelCallback = new PreparedModelCallback;
+    Return<ErrorStatus> prepareLaunchReturn = kDevice->prepareModel(model, preparedModelCallback);
+    ASSERT_TRUE(prepareLaunchReturn.isOk());
+    //     Note that preparation can fail for reasons other than an
+    //     invalid model (invalid model should result in
+    //     INVALID_ARGUMENT) -- for example, perhaps not all
+    //     operations are supported, or perhaps the device hit some
+    //     kind of capacity limit.
+    EXPECT_NE(prepareLaunchReturn, ErrorStatus::NONE);
+    EXPECT_NE(preparedModelCallback->getStatus(), ErrorStatus::NONE);
+    EXPECT_EQ(preparedModelCallback->getPreparedModel(), nullptr);
+}
+
 }  // namespace android::hardware::neuralnetworks::V1_0::vts::functional
diff --git a/neuralnetworks/1.0/vts/functional/Utils.cpp b/neuralnetworks/1.0/vts/functional/Utils.cpp
index 3613e69..32850b0 100644
--- a/neuralnetworks/1.0/vts/functional/Utils.cpp
+++ b/neuralnetworks/1.0/vts/functional/Utils.cpp
@@ -29,7 +29,11 @@
 
 #include <gtest/gtest.h>
 #include <algorithm>
+#include <cstring>
+#include <functional>
 #include <iostream>
+#include <map>
+#include <numeric>
 #include <vector>
 
 namespace android::hardware::neuralnetworks {
@@ -172,6 +176,45 @@
     return outputBuffers;
 }
 
+uint32_t sizeOfData(V1_0::OperandType type) {
+    switch (type) {
+        case V1_0::OperandType::FLOAT32:
+        case V1_0::OperandType::INT32:
+        case V1_0::OperandType::UINT32:
+        case V1_0::OperandType::TENSOR_FLOAT32:
+        case V1_0::OperandType::TENSOR_INT32:
+            return 4;
+        case V1_0::OperandType::TENSOR_QUANT8_ASYMM:
+            return 1;
+        default:
+            CHECK(false) << "Invalid OperandType " << static_cast<uint32_t>(type);
+            return 0;
+    }
+}
+
+static bool isTensor(V1_0::OperandType type) {
+    switch (type) {
+        case V1_0::OperandType::FLOAT32:
+        case V1_0::OperandType::INT32:
+        case V1_0::OperandType::UINT32:
+            return false;
+        case V1_0::OperandType::TENSOR_FLOAT32:
+        case V1_0::OperandType::TENSOR_INT32:
+        case V1_0::OperandType::TENSOR_QUANT8_ASYMM:
+            return true;
+        default:
+            CHECK(false) << "Invalid OperandType " << static_cast<uint32_t>(type);
+            return false;
+    }
+}
+
+uint32_t sizeOfData(const V1_0::Operand& operand) {
+    const uint32_t dataSize = sizeOfData(operand.type);
+    if (isTensor(operand.type) && operand.dimensions.size() == 0) return 0;
+    return std::accumulate(operand.dimensions.begin(), operand.dimensions.end(), dataSize,
+                           std::multiplies<>{});
+}
+
 std::string gtestCompliantName(std::string name) {
     // gtest test names must only contain alphanumeric characters
     std::replace_if(
diff --git a/neuralnetworks/1.0/vts/functional/ValidateModel.cpp b/neuralnetworks/1.0/vts/functional/ValidateModel.cpp
index 79d8594..5ffbd43 100644
--- a/neuralnetworks/1.0/vts/functional/ValidateModel.cpp
+++ b/neuralnetworks/1.0/vts/functional/ValidateModel.cpp
@@ -17,9 +17,14 @@
 #define LOG_TAG "neuralnetworks_hidl_hal_test"
 
 #include "1.0/Callbacks.h"
+#include "1.0/Utils.h"
 #include "GeneratedTestHarness.h"
 #include "VtsHalNeuralnetworks.h"
 
+#include <optional>
+#include <type_traits>
+#include <utility>
+
 namespace android::hardware::neuralnetworks::V1_0::vts::functional {
 
 using implementation::PreparedModelCallback;
@@ -67,26 +72,6 @@
     validatePrepareModel(device, message, model);
 }
 
-// Delete element from hidl_vec. hidl_vec doesn't support a "remove" operation,
-// so this is efficiently accomplished by moving the element to the end and
-// resizing the hidl_vec to one less.
-template <typename Type>
-static void hidl_vec_removeAt(hidl_vec<Type>* vec, uint32_t index) {
-    if (vec) {
-        std::rotate(vec->begin() + index, vec->begin() + index + 1, vec->end());
-        vec->resize(vec->size() - 1);
-    }
-}
-
-template <typename Type>
-static uint32_t hidl_vec_push_back(hidl_vec<Type>* vec, const Type& value) {
-    // assume vec is valid
-    const uint32_t index = vec->size();
-    vec->resize(index + 1);
-    (*vec)[index] = value;
-    return index;
-}
-
 static uint32_t addOperand(Model* model) {
     return hidl_vec_push_back(&model->operands,
                               {
@@ -107,6 +92,211 @@
     return index;
 }
 
+// If we introduce a CONSTANT_COPY for an operand of size operandSize,
+// how much will this increase the size of the model?  This assumes
+// that we can (re)use all of model.operandValues for the operand
+// value.
+static size_t constantCopyExtraSize(const Model& model, size_t operandSize) {
+    const size_t operandValuesSize = model.operandValues.size();
+    return (operandValuesSize < operandSize) ? (operandSize - operandValuesSize) : 0;
+}
+
+// Highly specialized utility routine for converting an operand to
+// CONSTANT_COPY lifetime.
+//
+// Expects that:
+// - operand has a known size
+// - operand->lifetime has already been set to CONSTANT_COPY
+// - operand->location has been zeroed out
+//
+// Does the following:
+// - initializes operand->location to point to the beginning of model->operandValues
+// - resizes model->operandValues (if necessary) to be large enough for the operand
+//   value, padding it with zeroes on the end
+//
+// Potential problem:
+// By changing the operand to CONSTANT_COPY lifetime, this function is effectively initializing the
+// operand with unspecified (but deterministic) data. This means that the model may be invalidated
+// in two ways: not only is the lifetime of CONSTANT_COPY invalid, but the operand's value in the
+// graph may also be invalid (e.g., if the operand is used as an activation code and has an invalid
+// value). For now, this should be fine because it just means we're not testing what we think we're
+// testing in certain cases; but we can handwave this and assume we're probabilistically likely to
+// exercise the validation code over the span of the entire test set and operand space.
+//
+// Aborts if the specified operand type is an extension type or OEM type.
+static void becomeConstantCopy(Model* model, Operand* operand) {
+    // sizeOfData will abort if the specified type is an extension type or OEM type.
+    const size_t sizeOfOperand = sizeOfData(*operand);
+    EXPECT_NE(sizeOfOperand, size_t(0));
+    operand->location.poolIndex = 0;
+    operand->location.offset = 0;
+    operand->location.length = sizeOfOperand;
+    if (model->operandValues.size() < sizeOfOperand) {
+        model->operandValues.resize(sizeOfOperand);
+    }
+}
+
+// The sizeForBinder() functions estimate the size of the
+// representation of a value when sent to binder.  It's probably a bit
+// of an under-estimate, because we don't know the size of the
+// metadata in the binder format (e.g., representation of the size of
+// a vector); but at least it adds up "big" things like vector
+// contents.  However, it doesn't treat inter-field or end-of-struct
+// padding in a methodical way -- there's no attempt to be consistent
+// in whether or not padding in the native (C++) representation
+// contributes to the estimated size for the binder representation;
+// and there's no attempt to understand what padding (if any) is
+// needed in the binder representation.
+//
+// This assumes that non-metadata uses a fixed length encoding (e.g.,
+// a uint32_t is always encoded in sizeof(uint32_t) bytes, rather than
+// using an encoding whose length is related to the magnitude of the
+// encoded value).
+
+template <typename Type>
+static size_t sizeForBinder(const Type& val) {
+    static_assert(std::is_trivially_copyable_v<std::remove_reference_t<Type>>,
+                  "expected a trivially copyable type");
+    return sizeof(val);
+}
+
+template <typename Type>
+static size_t sizeForBinder(const hidl_vec<Type>& vec) {
+    return std::accumulate(vec.begin(), vec.end(), 0,
+                           [](size_t acc, const Type& x) { return acc + sizeForBinder(x); });
+}
+
+template <>
+size_t sizeForBinder(const Operand& operand) {
+    size_t size = 0;
+
+    size += sizeForBinder(operand.type);
+    size += sizeForBinder(operand.dimensions);
+    size += sizeForBinder(operand.numberOfConsumers);
+    size += sizeForBinder(operand.scale);
+    size += sizeForBinder(operand.zeroPoint);
+    size += sizeForBinder(operand.lifetime);
+    size += sizeForBinder(operand.location);
+
+    return size;
+}
+
+template <>
+size_t sizeForBinder(const Operation& operation) {
+    size_t size = 0;
+
+    size += sizeForBinder(operation.type);
+    size += sizeForBinder(operation.inputs);
+    size += sizeForBinder(operation.outputs);
+
+    return size;
+}
+
+template <>
+size_t sizeForBinder(const hidl_string& name) {
+    return name.size();
+}
+
+template <>
+size_t sizeForBinder(const hidl_memory& memory) {
+    // This is just a guess.
+
+    size_t size = 0;
+
+    if (const native_handle_t* handle = memory.handle()) {
+        size += sizeof(*handle);
+        size += sizeof(handle->data[0] * (handle->numFds + handle->numInts));
+    }
+    size += sizeForBinder(memory.name());
+
+    return size;
+}
+
+template <>
+size_t sizeForBinder(const Model& model) {
+    size_t size = 0;
+
+    size += sizeForBinder(model.operands);
+    size += sizeForBinder(model.operations);
+    size += sizeForBinder(model.inputIndexes);
+    size += sizeForBinder(model.outputIndexes);
+    size += sizeForBinder(model.operandValues);
+    size += sizeForBinder(model.pools);
+
+    return size;
+}
+
+// https://developer.android.com/reference/android/os/TransactionTooLargeException.html
+//
+//     "The Binder transaction buffer has a limited fixed size,
+//     currently 1Mb, which is shared by all transactions in progress
+//     for the process."
+//
+// Will our representation fit under this limit?  There are two complications:
+// - Our representation size is just approximate (see sizeForBinder()).
+// - This object may not be the only occupant of the Binder transaction buffer.
+// So we'll be very conservative: We want the representation size to be no
+// larger than half the transaction buffer size.
+//
+// If our representation grows large enough that it still fits within
+// the transaction buffer but combined with other transactions may
+// exceed the buffer size, then we may see intermittent HAL transport
+// errors.
+static bool exceedsBinderSizeLimit(size_t representationSize) {
+    // Instead of using this fixed buffer size, we might instead be able to use
+    // ProcessState::self()->getMmapSize(). However, this has a potential
+    // problem: The binder/mmap size of the current process does not necessarily
+    // indicate the binder/mmap size of the service (i.e., the other process).
+    // The only way it would be a good indication is if both the current process
+    // and the service use the default size.
+    static const size_t kHalfBufferSize = 1024 * 1024 / 2;
+
+    return representationSize > kHalfBufferSize;
+}
+
+///////////////////////// VALIDATE EXECUTION ORDER ////////////////////////////
+
+static void mutateExecutionOrderTest(const sp<IDevice>& device, const V1_0::Model& model) {
+    for (size_t operation = 0; operation < model.operations.size(); ++operation) {
+        const Operation& operationObj = model.operations[operation];
+        for (uint32_t input : operationObj.inputs) {
+            if (model.operands[input].lifetime == OperandLifeTime::TEMPORARY_VARIABLE ||
+                model.operands[input].lifetime == OperandLifeTime::MODEL_OUTPUT) {
+                // This operation reads an operand written by some
+                // other operation.  Move this operation to the
+                // beginning of the sequence, ensuring that it reads
+                // the operand before that operand is written, thereby
+                // violating execution order rules.
+                const std::string message = "mutateExecutionOrderTest: operation " +
+                                            std::to_string(operation) + " is a reader";
+                validate(device, message, model, [operation](Model* model) {
+                    auto& operations = model->operations;
+                    std::rotate(operations.begin(), operations.begin() + operation,
+                                operations.begin() + operation + 1);
+                });
+                break;  // only need to do this once per operation
+            }
+        }
+        for (uint32_t output : operationObj.outputs) {
+            if (model.operands[output].numberOfConsumers > 0) {
+                // This operation writes an operand read by some other
+                // operation.  Move this operation to the end of the
+                // sequence, ensuring that it writes the operand after
+                // that operand is read, thereby violating execution
+                // order rules.
+                const std::string message = "mutateExecutionOrderTest: operation " +
+                                            std::to_string(operation) + " is a writer";
+                validate(device, message, model, [operation](Model* model) {
+                    auto& operations = model->operations;
+                    std::rotate(operations.begin() + operation, operations.begin() + operation + 1,
+                                operations.end());
+                });
+                break;  // only need to do this once per operation
+            }
+        }
+    }
+}
+
 ///////////////////////// VALIDATE MODEL OPERAND TYPE /////////////////////////
 
 static const int32_t invalidOperandTypes[] = {
@@ -218,9 +408,233 @@
     }
 }
 
+///////////////////////// VALIDATE OPERAND LIFETIME /////////////////////////////////////////////
+
+static std::vector<OperandLifeTime> getInvalidLifeTimes(const Model& model, size_t modelSize,
+                                                        const Operand& operand) {
+    // TODO: Support OperandLifeTime::CONSTANT_REFERENCE as an invalid lifetime
+    // TODO: Support OperandLifeTime::NO_VALUE as an invalid lifetime
+
+    // Ways to get an invalid lifetime:
+    // - change whether a lifetime means an operand should have a writer
+    std::vector<OperandLifeTime> ret;
+    switch (operand.lifetime) {
+        case OperandLifeTime::MODEL_OUTPUT:
+        case OperandLifeTime::TEMPORARY_VARIABLE:
+            ret = {
+                    OperandLifeTime::MODEL_INPUT,
+                    OperandLifeTime::CONSTANT_COPY,
+            };
+            break;
+        case OperandLifeTime::CONSTANT_COPY:
+        case OperandLifeTime::CONSTANT_REFERENCE:
+        case OperandLifeTime::MODEL_INPUT:
+            ret = {
+                    OperandLifeTime::TEMPORARY_VARIABLE,
+                    OperandLifeTime::MODEL_OUTPUT,
+            };
+            break;
+        case OperandLifeTime::NO_VALUE:
+            // Not enough information to know whether
+            // TEMPORARY_VARIABLE or CONSTANT_COPY would be invalid --
+            // is this operand written (then CONSTANT_COPY would be
+            // invalid) or not (then TEMPORARY_VARIABLE would be
+            // invalid)?
+            break;
+        default:
+            ADD_FAILURE();
+            break;
+    }
+
+    const size_t operandSize = sizeOfData(operand);  // will be zero if shape is unknown
+    if (!operandSize ||
+        exceedsBinderSizeLimit(modelSize + constantCopyExtraSize(model, operandSize))) {
+        // Unknown size or too-large size
+        ret.erase(std::remove(ret.begin(), ret.end(), OperandLifeTime::CONSTANT_COPY), ret.end());
+    }
+
+    return ret;
+}
+
+static void mutateOperandLifeTimeTest(const sp<IDevice>& device, const V1_0::Model& model) {
+    const size_t modelSize = sizeForBinder(model);
+    for (size_t operand = 0; operand < model.operands.size(); ++operand) {
+        const std::vector<OperandLifeTime> invalidLifeTimes =
+                getInvalidLifeTimes(model, modelSize, model.operands[operand]);
+        for (OperandLifeTime invalidLifeTime : invalidLifeTimes) {
+            const std::string message = "mutateOperandLifetimeTest: operand " +
+                                        std::to_string(operand) + " has lifetime " +
+                                        toString(invalidLifeTime) + " instead of lifetime " +
+                                        toString(model.operands[operand].lifetime);
+            validate(device, message, model, [operand, invalidLifeTime](Model* model) {
+                static const DataLocation kZeroDataLocation = {};
+                Operand& operandObj = model->operands[operand];
+                switch (operandObj.lifetime) {
+                    case OperandLifeTime::MODEL_INPUT: {
+                        hidl_vec_remove(&model->inputIndexes, uint32_t(operand));
+                        break;
+                    }
+                    case OperandLifeTime::MODEL_OUTPUT: {
+                        hidl_vec_remove(&model->outputIndexes, uint32_t(operand));
+                        break;
+                    }
+                    default:
+                        break;
+                }
+                operandObj.lifetime = invalidLifeTime;
+                operandObj.location = kZeroDataLocation;
+                switch (invalidLifeTime) {
+                    case OperandLifeTime::CONSTANT_COPY: {
+                        becomeConstantCopy(model, &operandObj);
+                        break;
+                    }
+                    case OperandLifeTime::MODEL_INPUT:
+                        hidl_vec_push_back(&model->inputIndexes, uint32_t(operand));
+                        break;
+                    case OperandLifeTime::MODEL_OUTPUT:
+                        hidl_vec_push_back(&model->outputIndexes, uint32_t(operand));
+                        break;
+                    default:
+                        break;
+                }
+            });
+        }
+    }
+}
+
+///////////////////////// VALIDATE OPERAND INPUT-or-OUTPUT //////////////////////////////////////
+
+static std::optional<OperandLifeTime> getInputOutputLifeTime(const Model& model, size_t modelSize,
+                                                             const Operand& operand) {
+    // Ways to get an invalid lifetime (with respect to model inputIndexes and outputIndexes):
+    // - change whether a lifetime means an operand is a model input, a model output, or neither
+    // - preserve whether or not a lifetime means an operand should have a writer
+    switch (operand.lifetime) {
+        case OperandLifeTime::CONSTANT_COPY:
+        case OperandLifeTime::CONSTANT_REFERENCE:
+            return OperandLifeTime::MODEL_INPUT;
+        case OperandLifeTime::MODEL_INPUT: {
+            const size_t operandSize = sizeOfData(operand);  // will be zero if shape is unknown
+            if (!operandSize ||
+                exceedsBinderSizeLimit(modelSize + constantCopyExtraSize(model, operandSize))) {
+                // Unknown size or too-large size
+                break;
+            }
+            return OperandLifeTime::CONSTANT_COPY;
+        }
+        case OperandLifeTime::MODEL_OUTPUT:
+            return OperandLifeTime::TEMPORARY_VARIABLE;
+        case OperandLifeTime::TEMPORARY_VARIABLE:
+            return OperandLifeTime::MODEL_OUTPUT;
+        case OperandLifeTime::NO_VALUE:
+            // Not enough information to know whether
+            // TEMPORARY_VARIABLE or CONSTANT_COPY would be an
+            // appropriate choice -- is this operand written (then
+            // TEMPORARY_VARIABLE would be appropriate) or not (then
+            // CONSTANT_COPY would be appropriate)?
+            break;
+        default:
+            ADD_FAILURE();
+            break;
+    }
+
+    return std::nullopt;
+}
+
+static void mutateOperandInputOutputTest(const sp<IDevice>& device, const V1_0::Model& model) {
+    const size_t modelSize = sizeForBinder(model);
+    for (size_t operand = 0; operand < model.operands.size(); ++operand) {
+        const std::optional<OperandLifeTime> changedLifeTime =
+                getInputOutputLifeTime(model, modelSize, model.operands[operand]);
+        if (changedLifeTime) {
+            const std::string message = "mutateOperandInputOutputTest: operand " +
+                                        std::to_string(operand) + " has lifetime " +
+                                        toString(*changedLifeTime) + " instead of lifetime " +
+                                        toString(model.operands[operand].lifetime);
+            validate(device, message, model, [operand, changedLifeTime](Model* model) {
+                static const DataLocation kZeroDataLocation = {};
+                Operand& operandObj = model->operands[operand];
+                operandObj.lifetime = *changedLifeTime;
+                operandObj.location = kZeroDataLocation;
+                if (*changedLifeTime == OperandLifeTime::CONSTANT_COPY) {
+                    becomeConstantCopy(model, &operandObj);
+                }
+            });
+        }
+    }
+}
+
+///////////////////////// VALIDATE OPERAND NUMBER OF CONSUMERS //////////////////////////////////
+
+static std::vector<uint32_t> getInvalidNumberOfConsumers(uint32_t numberOfConsumers) {
+    if (numberOfConsumers == 0) {
+        return {1};
+    } else {
+        return {numberOfConsumers - 1, numberOfConsumers + 1};
+    }
+}
+
+static void mutateOperandNumberOfConsumersTest(const sp<IDevice>& device,
+                                               const V1_0::Model& model) {
+    for (size_t operand = 0; operand < model.operands.size(); ++operand) {
+        const std::vector<uint32_t> invalidNumberOfConsumersVec =
+                getInvalidNumberOfConsumers(model.operands[operand].numberOfConsumers);
+        for (uint32_t invalidNumberOfConsumers : invalidNumberOfConsumersVec) {
+            const std::string message =
+                    "mutateOperandNumberOfConsumersTest: operand " + std::to_string(operand) +
+                    " numberOfConsumers = " + std::to_string(invalidNumberOfConsumers);
+            validate(device, message, model, [operand, invalidNumberOfConsumers](Model* model) {
+                model->operands[operand].numberOfConsumers = invalidNumberOfConsumers;
+            });
+        }
+    }
+}
+
+///////////////////////// VALIDATE OPERAND NUMBER OF WRITERS ////////////////////////////////////
+
+static void mutateOperandAddWriterTest(const sp<IDevice>& device, const V1_0::Model& model) {
+    for (size_t operation = 0; operation < model.operations.size(); ++operation) {
+        for (size_t badOutputNum = 0; badOutputNum < model.operations[operation].outputs.size();
+             ++badOutputNum) {
+            const uint32_t outputOperandIndex = model.operations[operation].outputs[badOutputNum];
+            const std::string message = "mutateOperandAddWriterTest: operation " +
+                                        std::to_string(operation) + " writes to " +
+                                        std::to_string(outputOperandIndex);
+            // We'll insert a copy of the operation, all of whose
+            // OTHER output operands are newly-created -- i.e.,
+            // there'll only be a duplicate write of ONE of that
+            // operation's output operands.
+            validate(device, message, model, [operation, badOutputNum](Model* model) {
+                Operation newOperation = model->operations[operation];
+                for (uint32_t input : newOperation.inputs) {
+                    ++model->operands[input].numberOfConsumers;
+                }
+                for (size_t outputNum = 0; outputNum < newOperation.outputs.size(); ++outputNum) {
+                    if (outputNum == badOutputNum) continue;
+
+                    Operand operandValue = model->operands[newOperation.outputs[outputNum]];
+                    operandValue.numberOfConsumers = 0;
+                    if (operandValue.lifetime == OperandLifeTime::MODEL_OUTPUT) {
+                        operandValue.lifetime = OperandLifeTime::TEMPORARY_VARIABLE;
+                    } else {
+                        ASSERT_EQ(operandValue.lifetime, OperandLifeTime::TEMPORARY_VARIABLE);
+                    }
+                    newOperation.outputs[outputNum] =
+                            hidl_vec_push_back(&model->operands, operandValue);
+                }
+                // Where do we insert the extra writer (a new
+                // operation)?  It has to be later than all the
+                // writers of its inputs.  The easiest thing to do
+                // is to insert it at the end of the operation
+                // sequence.
+                hidl_vec_push_back(&model->operations, newOperation);
+            });
+        }
+    }
+}
+
 ///////////////////////// VALIDATE EXTRA ??? /////////////////////////
 
-// TODO: Operand::lifetime
 // TODO: Operand::location
 
 ///////////////////////// VALIDATE OPERATION OPERAND TYPE /////////////////////////
@@ -351,6 +765,33 @@
     }
 }
 
+///////////////////////// VALIDATE MODEL OPERANDS WRITTEN ///////////////////////////////////////
+
+static void mutateOperationRemoveWriteTest(const sp<IDevice>& device, const V1_0::Model& model) {
+    for (size_t operation = 0; operation < model.operations.size(); ++operation) {
+        for (size_t outputNum = 0; outputNum < model.operations[operation].outputs.size();
+             ++outputNum) {
+            const uint32_t outputOperandIndex = model.operations[operation].outputs[outputNum];
+            if (model.operands[outputOperandIndex].numberOfConsumers > 0) {
+                const std::string message = "mutateOperationRemoveWriteTest: operation " +
+                                            std::to_string(operation) + " writes to " +
+                                            std::to_string(outputOperandIndex);
+                validate(device, message, model, [operation, outputNum](Model* model) {
+                    uint32_t& outputOperandIndex = model->operations[operation].outputs[outputNum];
+                    Operand operandValue = model->operands[outputOperandIndex];
+                    operandValue.numberOfConsumers = 0;
+                    if (operandValue.lifetime == OperandLifeTime::MODEL_OUTPUT) {
+                        operandValue.lifetime = OperandLifeTime::TEMPORARY_VARIABLE;
+                    } else {
+                        ASSERT_EQ(operandValue.lifetime, OperandLifeTime::TEMPORARY_VARIABLE);
+                    }
+                    outputOperandIndex = hidl_vec_push_back(&model->operands, operandValue);
+                });
+            }
+        }
+    }
+}
+
 ///////////////////////// REMOVE OPERAND FROM EVERYTHING /////////////////////////
 
 static void removeValueAndDecrementGreaterValues(hidl_vec<uint32_t>* vec, uint32_t value) {
@@ -476,14 +917,20 @@
 ////////////////////////// ENTRY POINT //////////////////////////////
 
 void validateModel(const sp<IDevice>& device, const Model& model) {
+    mutateExecutionOrderTest(device, model);
     mutateOperandTypeTest(device, model);
     mutateOperandRankTest(device, model);
     mutateOperandScaleTest(device, model);
     mutateOperandZeroPointTest(device, model);
+    mutateOperandLifeTimeTest(device, model);
+    mutateOperandInputOutputTest(device, model);
+    mutateOperandNumberOfConsumersTest(device, model);
+    mutateOperandAddWriterTest(device, model);
     mutateOperationOperandTypeTest(device, model);
     mutateOperationTypeTest(device, model);
     mutateOperationInputOperandIndexTest(device, model);
     mutateOperationOutputOperandIndexTest(device, model);
+    mutateOperationRemoveWriteTest(device, model);
     removeOperandTest(device, model);
     removeOperationTest(device, model);
     removeOperationInputTest(device, model);
diff --git a/neuralnetworks/1.0/vts/functional/include/1.0/Utils.h b/neuralnetworks/1.0/vts/functional/include/1.0/Utils.h
index 3292f79..7bd0460 100644
--- a/neuralnetworks/1.0/vts/functional/include/1.0/Utils.h
+++ b/neuralnetworks/1.0/vts/functional/include/1.0/Utils.h
@@ -21,6 +21,7 @@
 #include <android/hardware/neuralnetworks/1.0/types.h>
 #include <android/hardware_buffer.h>
 #include <android/hidl/memory/1.0/IMemory.h>
+#include <gtest/gtest.h>
 #include <algorithm>
 #include <iosfwd>
 #include <string>
@@ -108,6 +109,15 @@
     vec->resize(vec->size() - 1);
 }
 
+// Assumes there is exactly one instance of the value in the vector.
+template <typename Type>
+inline void hidl_vec_remove(hidl_vec<Type>* vec, const Type& val) {
+    CHECK(vec != nullptr);
+    auto where = std::find(vec->begin(), vec->end(), val);
+    ASSERT_NE(where, vec->end());
+    hidl_vec_removeAt(vec, where - vec->begin());
+}
+
 template <typename Type>
 inline uint32_t hidl_vec_push_back(hidl_vec<Type>* vec, const Type& value) {
     CHECK(vec != nullptr);
@@ -117,6 +127,18 @@
     return index;
 }
 
+// Returns the amount of space needed to store a value of the specified type.
+//
+// Aborts if the specified type is an extension type or OEM type.
+uint32_t sizeOfData(V1_0::OperandType type);
+
+// Returns the amount of space needed to store a value of the dimensions and
+// type of this operand. For a non-extension, non-OEM tensor with unspecified
+// rank or at least one unspecified dimension, returns zero.
+//
+// Aborts if the specified type is an extension type or OEM type.
+uint32_t sizeOfData(const V1_0::Operand& operand);
+
 template <typename Type>
 using Named = std::pair<std::string, Type>;