use blowup factor of 2 and set extesion to 3 in p3

Author: jotabulacios

bench_vs_plonky3/benches/stark_comparison.rs

@@ -27,12 +27,13 @@ const NUM_SEQUENCES: usize = 16;
 const ROWS: usize = 1 << 18;
 const TRACE_LABEL: &str = "fib_pair_16seq_2^18";
 
-/// Proof options matching Lambda's `profile_prover.rs`:
-/// blowup=4, 100 queries, no grinding — production-like settings.
+/// Production proof options: blowup=2, 219 queries (from
+/// `GoldilocksCubicProofOptions::with_blowup(2)`), grinding=0 (excluded
+/// from benchmark — identical PoW work on both sides, not informative).
 fn benchmark_proof_options() -> ProofOptions {
     ProofOptions {
-        blowup_factor: 4,
-        fri_number_of_queries: 100,
+        blowup_factor: 2,
+        fri_number_of_queries: 219,
         coset_offset: 3,
         grinding_factor: 0,
     }

bench_vs_plonky3/src/lib.rs

@@ -22,8 +22,8 @@ mod tests {
 
     fn benchmark_proof_options() -> ProofOptions {
         ProofOptions {
-            blowup_factor: 4,
-            fri_number_of_queries: 100,
+            blowup_factor: 2,
+            fri_number_of_queries: 219,
             coset_offset: 3,
             grinding_factor: 0,
         }

bench_vs_plonky3/src/plonky3_config.rs

@@ -10,7 +10,9 @@ use p3_symmetric::{CompressionFunctionFromHasher, PaddingFreeSponge, Serializing
 use p3_uni_stark::StarkConfig;
 
 pub type Val = Goldilocks;
-pub type Challenge = BinomialExtensionField<Val, 2>;
+/// Degree-3 cubic extension, same as Lambda's `Degree3GoldilocksExtensionField`.
+/// Irreducible: x^3 - 2 (W = 2). Implemented in vendor-p3-goldilocks.
+pub type Challenge = BinomialExtensionField<Val, 3>;
 
 type ByteHash = Keccak256Hash;
 type U64Hash = PaddingFreeSponge<KeccakF, 25, 17, 4>;
@@ -42,18 +44,20 @@ fn build_mmcs() -> (ValMmcs, ChallengeMmcs, ByteHash) {
 }
 
 /// Creates a Plonky3 STARK config with parameters matched to Lambda's
-/// `profile_prover.rs`: blowup=4, 100 FRI queries, no grinding.
+/// production config `GoldilocksCubicProofOptions::with_blowup(2)`:
+/// blowup=2, 219 FRI queries, grinding=0 (excluded from benchmark).
 pub fn matched_params_config() -> P3Config {
     let (val_mmcs, challenge_mmcs, byte_hash) = build_mmcs();
     let dft = Dft::default();
     let challenger = Challenger::from_hasher(vec![], byte_hash);
 
-    // Match Lambda's profile_prover: blowup=4, queries=100, grinding=0.
+    // Match Lambda production: blowup=2, queries=219, grinding=0.
+    // Grinding excluded from benchmark (identical PoW on both sides).
     let fri_params = FriParameters {
-        log_blowup: 2, // blowup = 4
+        log_blowup: 1, // blowup = 2
         log_final_poly_len: 0,
         max_log_arity: 1,
-        num_queries: 100,
+        num_queries: 219,
         commit_proof_of_work_bits: 0,
         query_proof_of_work_bits: 0,
         mmcs: challenge_mmcs,

bench_vs_plonky3/vendor-p3-goldilocks/src/extension.rs

@@ -35,6 +35,32 @@ impl HasTwoAdicBinomialExtension<2> for Goldilocks {
     }
 }
 
+impl BinomiallyExtendableAlgebra<Self, 3> for Goldilocks {}
+
+impl BinomiallyExtendable<3> for Goldilocks {
+    // Verifiable in Sage with
+    // `R.<x> = GF(p)[]; assert (x^3 - 2).is_irreducible()`.
+    // Same irreducible as Lambda's Degree3GoldilocksExtensionField.
+    const W: Self = Self::new(2);
+
+    // DTH_ROOT = primitive 3rd root of unity = 7^((p-1)/3) mod p.
+    const DTH_ROOT: Self = Self::new(18446744065119617025);
+
+    // Generator of GF(p^3)* = 5 + w. Verified: passes order checks for
+    // all small prime factors of p^3 - 1.
+    const EXT_GENERATOR: [Self; 3] = [Self::new(5), Self::ONE, Self::ZERO];
+}
+
+impl HasTwoAdicBinomialExtension<3> for Goldilocks {
+    // v_2(p^3 - 1) = v_2(p-1) + v_2(p^2+p+1) = 32 + 0 = 32.
+    const EXT_TWO_ADICITY: usize = 32;
+
+    fn ext_two_adic_generator(bits: usize) -> [Self; 3] {
+        assert!(bits <= 32);
+        field_to_array(Self::two_adic_generator(bits))
+    }
+}
+
 impl BinomiallyExtendableAlgebra<Self, 5> for Goldilocks {}
 
 impl BinomiallyExtendable<5> for Goldilocks {