Reverse one byte · identity

L2.R1.reverse-1

Native verification status · ● solved

What this result establishes

256-value first-byte sweep. Every first-byte value is tested for each of 1 cases over 256 epochs. The remaining input bytes are public deterministic samples. This does not exhaust all input strings or prove suffix independence.

Placement: Verified canonical or tool baseline. Similar slots are retained for historical continuity. How rank is interpreted.

Challenge

ladder rank: #4 (historical identifier L2)
family / transform: Transform / Reverse
cases: 1 case, 1 output byte each
limits: program ≤ 256 bytes, ≤ 2048 steps/case
task summary: A one-byte reversal leaves the byte unchanged.
exact contract: Registry JSON · L2.R1.reverse-1

Winning program

solutions/echo/echo-first-byte.mal · 3 bytes canonical (4 on disk) · sha256 canonical 681f8033410df7a4a5d7eaa3f8c730929459de77ed4fd27cac02cd813ab36c0c · file 7e06b0c66f3253e37e419ad8b59365950c5d484db497487c95a4bad6cc1bb2a7

ubO

Solver

name: ubO (canonical)
type: canonical
metric: 1/1 case, 5 seeds
attribution notes: Minimal 3-instruction classic-Malbolge program (IN, OUT, HALT); long predates this project.

Task notes

A one-byte reversal leaves the byte unchanged.

Earlier record notes

Retained for provenance; these notes may predate current calibration. See the verification scope and placement rationale above.

1-byte reverse is the identity, so ubO passes; the registry marks this a transform-family sanity check.

Verification transcript (native VM, 256 epochs)

Exhaustive sweep: epoch i pins case j's first byte to (i + j) mod 256, so the 256 epochs cover every first byte for every case. Aggregate: 256/256 case-runs correct.

Reproduce

git clone https://github.com/oklo/malbolge-rungs
cargo run -p harness -- verify --rung L2.R1.reverse-1 --program solutions/echo/echo-first-byte.mal --epochs 256 --verbose