Explanation of post in IndisputableMonolith.LedgerPostingAdjacency
(1) In plain English: post is a function that takes an existing ledger state L (debit and credit integer counts across d accounts), a specific account index k, and a side (debit or credit). It returns a new ledger state identical to L except that exactly one unit is added to the chosen side's count at account k.
(2) Why it matters in Recognition Science: This encodes atomic ledger updates as single-unit postings. Such an update changes the phi vector (debit minus credit) by exactly +1 or -1 at one coordinate. The change flips exactly one bit in the associated parity pattern, directly linking ledger mechanics to one-bit adjacency. This supplies the missing glue between ledger language and the parity/Gray adjacency results.
(3) How to read the formal statement: The declaration is noncomputable def post {d : Nat} (L : LedgerState d) (k : Fin d) (side : Side) : LedgerState d. It uses classical choice and pattern-matches on side. For debit it defines a new debit map that increments only at k; for credit it does the same on the credit map. The definition is accompanied by simp lemmas that compute the resulting phiVec exactly.
(4) Visible dependencies or certificates in the supplied source: Imports Recognition, LedgerParityAdjacency, and Cost.Jlog. Key supporting declarations include phiVec_post_debit, phiVec_post_credit, phiVec_coordAtomicStep_of_post, and parity_oneBitDiff_of_post. The module also defines PostingStep and proves postingStep_oneBitDiff.
(5) What this declaration does not prove: It establishes only a mathematical model of ledger updates and their parity effect. It does not prove that physical reality must implement recognition via this exact posting mechanism, nor does it derive the full forcing chain or supply empirical falsifiers for the model.