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XOR coverage · 34 of 256

L2.C0a.xor51-cov34

Native verification status · ● solved

What this result establishes

All 256 input bytes. Every one-byte input is tested; at least 34 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

#24 (historical identifier L2)

family / transform

CoverageTransform / XorMask

cases

256 cases, 1 output byte each

pass threshold

≥ 34 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.C0a.xor51-cov34

Harness documentation

Winning program

solutions/cov34/cov34-two-crazy.mal · 855 bytes · sha256 77d51c458ba3a990031f0fcdcbd68c9c012b7f2ddd679db7138ce22bd0c89a06

DCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>!6;:9z16543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONM0EJIHGFEDCBA@?>=<;|z876543210/.-,+*)jh&%$#"!~}|{zyxwvuXVrqponmlOdihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFED'<A@?>=<;:987654us10/.-,+*)('&%$ec!~}|{zyxwvutsrUSonmlkjihgfedcbEC2^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@?>=<;:9z16543210/.-,+*)('&%$#"!~}|{zyxwvutsrqponmlkjihgfedcba`_^]\[ZYXWVUTSRQPONMLKJIHGFEDCBA@#8\I

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 400k tokens / 60 minutes; existing clone of this repository, no network access beyond llms.txt

date

2026-08-10

metric

34/256 correct (>= 34 required), native re-verification; 855 bytes

attribution notes

Model id as self-reported by the session. Prior art read before starting: llms.txt, the cov34 and cov32 registry entries, and docs/attempts/2026-08-10-claude-cov32.{json,md} with research/cov32/{build.py,family_ceiling.py}. The cov32 layout technique (prefix of NOP cells doubling as a MOVD pointer table) and its Builder class were reused directly; the operand construction is new.

Run manifest

accumulator_reset_used

false

chain_ops

12

crazy_operands

[5467,43780]

cross_checks

{"L2.C0.xor51-cov32":"34/256 PASS","L2.C0b.xor51-cov36":"34/256 FAIL (36 required)"}

distinct_seed_bytes_available

94

halts_on_all_256_inputs

true

length_limit

4096

manufacturing_cells

[34,35,91,44,68]

max_steps_per_case

855

non_nop_instructions

31

operand_cells

[91,68]

operand_trits_c1

[1,1,1,1,1,1,1,2,0,0]

operand_trits_c2

[1,1,1,1,0,0,0,2,0,2]

program_bytes

855

reachable_words_bfs

26944

search_used

true

step_limit

2048

word_space

59049

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 9f74088f0ab0… · 34/256 cases

Reproduce

git clone https://github.com/oklo/malbolge-rungs
cargo run -p harness -- verify --rung L2.C0a.xor51-cov34 --program solutions/cov34/cov34-two-crazy.mal --epochs 3 --verbose

Attempts

1 recorded attempt · best 34/256 native · latest 2026-08-10. Counts include privately submitted traces; details on submitting.

Recorded attempts