The earlier statement that did not travel
A subject the papers are about. The loosest grouping, and the one to reach for last.
Results that were published, correctly, years before the work everyone credits -- held here in pairs, so the earlier statement sits beside the one that travelled.
The membership criterion is evidential rather than topical: each pair is one where the corpus itself holds the documentation, not where the claim is merely well known. Three pairs qualify.
*Reverse Hoare logic, 2011, before incorrectness logic, 2020.* The strongest case, because the later paper says so in its own text: O'Hearn writes 'I acknowledge the priority of de Vries and Koutavas', and thanks Emanuele D'Osualdo for pointing the earlier work out to him -- so he found it afterwards. Nine years, the same shape of triple, and the 2011 SEFM paper did not travel.
*Trap door insertion, 1974, before Reflections on Trusting Trust, 1984.* Thompson's Turing lecture was built on Section 3.4.5 of Karger and Schell's Multics security evaluation, held here as the 2002 reprint. The lecture is the memorable statement, not the first one.
*The axioms, 1861 and 1888, before 1889.* Wang's 1957 paper put Grassmann's textbook back into the story thirty years before Peano; Kahle's title states the other half -- Dedekind proved as theorems what Peano set down as axioms a year later. The name attached to the axioms is the one thing in that literature nobody defends. Both originals are held, in German, in `the-axioms-before-peano`.
A fourth case is close but different in kind and is deliberately not here: `turing1949checking` precedes Floyd and Hoare, and O'Hearn's 2019 survey gives that lineage, but a descent acknowledged by the field is not the same as a priority that went unnoticed.
What the pairs have in common is not injustice. It is that the memorable statement and the first statement are different documents, and a bibliography that holds only the memorable one cannot tell you that. Each pair also sits in its own topical set, where it does ordinary work; the point of gathering them is that the pattern is only visible across subjects.