ABI Layer 3: transitivity of multi-step disclosure reachability#39
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Add Mylangiser.ABI.Semantics, a machine-checked flagship proof for the
headline domain property: progressive-disclosure interfaces only ever ADD
revealed items across steps, never remove a previously-shown one.
Model: a disclosure run is a sequence of revealed-item sets (List (List Nat)).
A valid step Reveal before after exists only when Subset before after holds
(every item visible before is still visible after) — there is no constructor
that drops a revealed item. MonotoneRun is the transitive closure over steps.
Includes a sound+complete decision procedure (decSubset, decReveal, decRun),
a certifier into the ABI Result type with a soundness lemma (certifyRunSound),
a positive control (goodRunMonotone: {1}->{1,2}->{1,2,3}) and a negative
control (hidingStepInvalid / hidingRunNotMonotone: {1,2}->{1} has no valid
transition proof). No believe_me/postulate/assert — fully total.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Adds a second, deeper, distinct machine-checked theorem over the existing Semantics model. Where Layer 2 proves single-step monotonicity (one Reveal step may only add items), Layer 3 proves the multi-step disclosure relation Reaches is transitive (reachesTrans) and that reachability implies a global Subset (reachesImpliesSubset) — revealed sets only grow across many steps, a fact not implied by the local theorem. Includes the load-bearing algebraic laws subsetElem/subsetTrans/subsetRefl, a sound+complete decision procedure, a Result certifier with soundness extraction, a positive control (concrete two-hop reachability witness whose growth is machine-derived), a composed-path witness via transitivity, and negative/non-vacuity controls (hidingNotSubset, hidingNotReachable, hidingCertifyRejected). Builds clean with zero warnings; adversarial false claims are rejected by the checker. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
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Summary
Layer 3 (second, deeper invariant): proves transitivity of multi-step disclosure reachability — a disclosure reachable from a reachable disclosure is reachable, so revealed sets only grow across many steps. Distinct from and deeper than the Layer-2 single-step monotonicity.
New module
Mylangiser.ABI.Invariants(imports the Layer-2Semanticsmodel). Positive + non-vacuity controls.Testing
Idris2 0.7.0
--build→ exit 0, zero warnings. Adversarial rejection confirmed.build/removed. Nobelieve_me/postulate/sorry.🤖 Generated with Claude Code
https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Generated by Claude Code