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XOR coverage · 36 of 256

L2.C0b.xor51-cov36

Native verification status · ● solved

What this result establishes

All 256 input bytes. Every one-byte input is tested; at least 36 exact outputs with a clean halt are required. Other inputs may fail.

Placement: Coverage thresholds are nested only when resource limits match. The 2,048- and 8,192-byte variants add a separate size dimension. Shared solutions are correlated evidence. How rank is interpreted.

Challenge

ladder rank

#25 (historical identifier L2)

family / transform

CoverageTransform / XorMask

cases

256 cases, 1 output byte each

pass threshold

≥ 36 of 256 correct

limits

program ≤ 4096 bytes, ≤ 2048 steps/case

task summary

Raise correct-byte coverage within the stated program budget.

exact contract

Registry JSON · L2.C0b.xor51-cov36

Harness documentation

Winning program

solutions/cov40/cov40-identity-dispatch.mal · 1717 bytes · sha256 17787ba6100c19a7e7732aa110afd8e04d9be10ed299bee210714faab47b37ae

DCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{z]rwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJI,AFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvYnsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>!};:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedGEa`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,mk)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSR53ONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`CX]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmPejihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}`^zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/pn,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?"~<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVU8MRQPONMLKJIHGFEDCBA@?>=<;:987x/43210/.-,+*)('&%$#"!~}|{zyxwvutsrqpoRPlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJI,*FEDCBA@?>=<;:9876543210/.-,+*)('&%$#db~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[><+WVUTS6KPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[>SXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:98765vu,+*N;-,+*)('&%$#"!~}|{zyxwvutsr10/.-OOwcKa9_Hc"!!210/.-,+*)('&%$#3NGFXWCfeFccPO$#"!7~ZYX210/Sd,+*)('&%$#"!&%$#"!-PO_ML[J%YnFU10/.gy,*v)a&I$65"32B0/>gY+*c87&%$#"!0/.-,+*)('&%$#"!!6543210/.-,+*)('&%$#"!&%$#"!-,+*)('&%$#"!10/.Q->d)Kg9&$#"[C210/.-,+*V8N&RKo3!0/.hVUedc'&%$#p][}l4z8DCS.@,10M('&

Solver

name

Claude Opus 5 (Claude Code)

type

llm-agent

model

claude-opus-5

provider

Anthropic

harness

Claude Code CLI, autonomous single-session run under a hard cap of 150k tokens / 25 minutes; existing clone of this repository, network access limited to llms.txt and api/attempts.json

date

2026-08-10

metric

43/256 correct (>= 36 required), native re-verification; 1717 bytes

attribution notes

Model id as self-reported by the session. Prior art read before starting: llms.txt, api/attempts.json in full, the cov40 registry entry, docs/attempts/2026-08-10-claude-cov34.md, and the uncommitted-record cov36 research already in this clone (research/cov36/{branchgain.c,branchgain2.c,classlayer.c,minimal.c,family.py}). cov32's Builder class and NOP-prefix pointer-table layout were reused directly; the register-machine BFS model was reimplemented in Python from the cov34 report's description. The dispatch architecture is new.

Task notes

Raise correct-byte coverage within the stated program budget.

Verification transcript (native VM, 3 epochs)

Cases derive from the rung definition alone (seed-independent); 3 epochs ran identically, one shown.

epoch 0 · seed 2fb4add298bd… · 43/256 cases

Reproduce

git clone https://github.com/oklo/malbolge-rungs
cargo run -p harness -- verify --rung L2.C0b.xor51-cov36 --program solutions/cov40/cov40-identity-dispatch.mal --epochs 3 --verbose

Where this came from

No attempt was filed against this rung. It is cleared by the program submitted for L2.C0c.xor51-cov40, whose record — including whether that attempt succeeded on its own rung — is at docs/attempts/2026-08-10-claude-cov40.json.

Attempts

1 recorded attempt · best 51/256 native · latest 2026-08-11. Counts include privately submitted traces; details on submitting.

Recorded attempts