Add five-source arity-four connector cost bound

[1337isnot1337]

Summary

Adds a scoped five-source bound for one paid connector alphabet extension: an atomic arity-four source event Q_r: z += sum_{j != r} B_j x_j, charged one dispatch plus all four constituent source-map additions.

For the all-31-nonzero-mask paired-readout batch, the original alphabet has exact 74-query cost, or 148 units under the stated dispatch-plus-addition ledger. Every schedule using the new family costs at least 149 units. The exceptional one-Q, nine-source-event branch is exhaustively checked: 23,184 normalized words, maximum prefix-difference set size 26/32. No kappa or supplier admission is claimed.

Package: research/five-source-arity-four-bound/
Base: 20ecf2891d80b5acf18d980b2164fb44ea7faa90
Head: 0133b60e

Verification

• python3 -B research/universal-connector-boundary/verify.py — 945-pairing predecessor control passes.
• python3.12 -I -O -B research/five-source-arity-four-bound/verify.py — dirty-call control, 23,184-word census, symmetry controls and twelve-event positive control pass.
• python3.12 scripts/research_package.py --package research/five-source-arity-four-bound — registered package replay passes.
• python3.12 scripts/research_package.py --package research/five-source-arity-four-bound --check-only — package metadata and source pins pass.

Scope and limits

This uses the exact five-source dirty connector and output boundary, with the source alphabet expanded only by weight-four steps. The result uses a uniform linear charge of one unit per event dispatch and one per constituent map addition. It does not price a physical caller's nonuniform source tariffs, word-dependent storage/routing, or an implementation that performs fewer than four charged additions. It is not a complete multiplication theorem or a new selected bound. The selected cold replay and hosted CI were not run or claimed.

Credit Ross Richardson's #943/#934 connector lineage and Cinna Davis's open #2249 high-arity six-source work. #2249 motivated the complementary five-source question but was not independently replayed here. Prepared by OpenAI Codex with substantial AI assistance; no independent human or proof-assistant review is claimed.

Publication validation

The registered package replay passed on CPython 3.12.3 with python3.12 scripts/research_package.py --package research/five-source-arity-four-bound. The optional --check-source-history preflight could not run because this MacBook checkout is shallow and the checker requires full Git history. This package's source manifest pins only files at its exact base commit 20ecf2891d80b5acf18d980b2164fb44ea7faa90; it contains no head: source pins. Any earlier pending note above refers to the state before this publication-time replay.