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AztecProtocol · Oct 2, 2023 · 3d68467 · 3d68467
1 parent 658094e
commit 3d68467
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Showing 3 changed files with 13 additions and 7 deletions.
diff --git a/...nberg/cpp/src/barretenberg/proof_system/circuit_builder/baby_vm/baby_vm_trace_builder.hpp b/...nberg/cpp/src/barretenberg/proof_system/circuit_builder/baby_vm/baby_vm_trace_builder.hpp
@@ -20,6 +20,8 @@ class BabyVMTraceBuilder : public ExecutionTraceBuilderBase<arithmetization::Bab
     std::vector<Row> rows;
     // WORKTODO: instead store columns as vectors? This is what we do with circuit builders.
 
+
+    // EXERCISE NOTE: In practice, some operations will span multiple execution trace rows.
     void add_accumulate(const FF& to_add)
     {
         vm_operations.emplace_back(VMOperation{
@@ -52,6 +54,7 @@ class BabyVMTraceBuilder : public ExecutionTraceBuilderBase<arithmetization::Bab
         });
     }
 
+    // EXERCISE NOTE: add error case and error handling?
     void build_execution_trace()
     {
         FF previous_accumulator = 0;

diff --git a/.../cpp/src/barretenberg/proof_system/circuit_builder/baby_vm/baby_vm_trace_builder.test.cpp b/.../cpp/src/barretenberg/proof_system/circuit_builder/baby_vm/baby_vm_trace_builder.test.cpp
@@ -24,7 +24,7 @@ TEST(BabyVMTraceBuilderTests, Basic)
         trace.mul_accumulate(b);
         trace.mul_accumulate(x);
         trace.add_accumulate(a);
-        trace.eq_and_reset(expected);
+        trace.eq_and_reset(1);
 
         bool result = trace.check_gates();
         EXPECT_EQ(result, expected_result);

diff --git a/barretenberg/cpp/src/barretenberg/proof_system/relations/baby_vm/baby_vm_relation.hpp b/barretenberg/cpp/src/barretenberg/proof_system/relations/baby_vm/baby_vm_relation.hpp
@@ -30,13 +30,13 @@ template <typename FF_> class BabyVMRelationImpl {
 
     /**
      * @brief Expression for the BabyVMMultiplication gate.
-     * @details The relation is defined as, for some challenge c,
+     * @details The relation is defined as, for some challenge c (the scaling factor),
      *
-     *     c^0 + (1 - q_mul) *      q_mul
-     *     c^1 + (1 - q_add) *      q_add
-     *     c^2 + (1 - q_add) * (1 - q_mul) * (accumulator - scalar)
-     *     c^3 + (1 - q_mul) *      q_add  * (accumulator - (previous_accumulator + scalar))
-     *     c^4 + (1 - q_add) *      q_mul  * (accumulator - (previous_accumulator * scalar))
+     *     c^0 * (1 - q_mul) *      q_mul
+     *   + c^1 * (1 - q_add) *      q_add
+     *   + c^2 * (1 - q_add) * (1 - q_mul) * (accumulator - scalar)
+     *   + c^3 * (1 - q_mul) *      q_add  * (accumulator - (previous_accumulator + scalar))
+     *   + c^4 * (1 - q_add) *      q_mul  * (accumulator - (previous_accumulator * scalar))
      *
      * @param accumulator the term being calculated by a sequence of calls to this function
      * @param new_term the term added to the accumulator in this iteration of the function
@@ -80,6 +80,7 @@ template <typename FF_> class BabyVMRelationImpl {
             auto tmp = (FF(1) - q_add);
             tmp *= (FF(1) - q_mul);
             tmp *= (accumulator - scalar);
+            tmp *= scaling_factor;
             std::get<2>(accumulators) += tmp;
         }();
 
@@ -88,6 +89,7 @@ template <typename FF_> class BabyVMRelationImpl {
             auto tmp = (FF(1) - q_mul);
             tmp *= q_add;
             tmp *= (accumulator - (previous_accumulator + scalar));
+            tmp *= scaling_factor;
             std::get<3>(accumulators) += tmp;
         }();
 
@@ -96,6 +98,7 @@ template <typename FF_> class BabyVMRelationImpl {
             auto tmp = (FF(1) - q_add);
             tmp *= q_mul;
             tmp *= (accumulator - (previous_accumulator * scalar));
+            tmp *= scaling_factor;
             std::get<4>(accumulators) += tmp;
         }();
     };