R56 exact backward reasoning
R56 backward reasoning showed that a registered target predicate could be decided with 392 of 512 semantic bits, corresponding to an exact 23.44% elimination under that diagnostic model. Current work asks whether exact primitives can compose into a cheaper end-to-end path.
- Published
- 2026-08-14
- Updated
- 2026-08-22
- Authors
- BTC PoW Lab
- Replication
- Exact primitive validated; composition research active
Local structure, statistical signal and operational advantage are evaluated separately.
Question
Can exact late-round constraints be composed without losing their diagnostic savings to transport, carry and implementation costs?
Hypothesis
Some exact partial evaluations may remain useful when composed across adjacent rounds and real job contexts.
Why this matters
Local elimination is only meaningful if the total pipeline, including state construction and dispatch, is cheaper than hashing.
Method
Build exact late-round oracles, measure semantic work, transport required context backward and audit every reject against full SHA-256.
Experimental setup
- Baseline
- Complete equivalent SHA-256 candidate evaluation.
- Setup
- Registered B8 predicate and exact backward model around R56.
- Hardware
- Classical verifier now; stock-ASIC compatibility is a later gate.
- Dataset
- Exact oracle and canonical subengine reports V1–V75.
Results
- 392 of 512 semantic bits were sufficient under the R56 model.
- Equivalent diagnostic elimination: approximately 23.44%.
- End-to-end composition remains unresolved.
Scientific analysis
The R56 program studies the exact dependency cone of a registered B8 predicate near the end of the second SHA-256 compression. A boundary variable is removable only when the compiled predicate is functionally independent of it, with every decision audited against the full oracle.
Exact elimination reduced the boundary representation from 512 semantic bits to 392. The 120 removed bits include complete W61–W63 words and W60[8..31] in the registered model. This describes functional support, not CPU instructions, gates, joules or nonce-space reduction.
The remaining 392 bits are individually relevant under cofactor tests, while composition and reachability remain separate questions. A smaller exact boundary can still be more expensive overall once the forward path required to produce it is charged.
Mathematical formulation
elimination = (512 − 392) / 512 = 23.4375%This is exact semantic support removed at the R56 boundary.
f_R56(x₁…x₅₁₂) = g(xᵢ : i ∈ S), |S| = 392The compiled predicate depends only on the support set S under the registered model.
Ctotal = Cforward + Cboundary + Cfallback + CdispatchOnly total charged cost can be compared with full equivalent hashing.
Statistical reading
Validation used 65,536 reachable states plus 4,096 synthetic frontiers with zero observed discrepancies for the support recompilation.
Zero mismatches supports implementation correctness on audited cohorts; exactness ultimately rests on construction/proof contracts, not on treating zero errors as proof by sampling.
Reachability projection and physical speed remain open or negative in later gates; neither is implied by a 23.44% support reduction.
Validity and scope
- Exact within the registered B8/R56 model.
- Semantic bits are not interchangeable with native gate count or energy.
- No reduction of Bitcoin nonce entropy or stock-ASIC speedup has been demonstrated.
Methodological references
Interpretation
This is an exact reasoning primitive, not a measured mining speedup. The research remains active because transport and runtime economics are not yet closed.
Limitations
- Semantic-bit work is not gate count, native cycles or joules.
- No complete stock-ASIC path has been demonstrated.
Reproduction
Validate every partial reject against the golden full-round oracle on free-frontier and reachable Bitcoin-format cohorts.
Artifacts
The first seventy-five subengine experiment summaries are published in the experiment log.
Experimental content is provided for research and educational use, without warranty. Validate independently before relying on it. Read the full disclaimer.