Capture: Dedupe-check on '[ANSWERED 2026-07-07, cycle 17] No — never on the page (Wayback 2014–2026)' topic — confirms fold-in into claim-linnainmaa-copenhagen-anecdote point 3 is real, no new research performed
What was checked
The core question behind this topic (harvested from the 2026-06-28 Griewank-verification capture) was: did Jürgen Schmidhuber's essay "Who Invented Backpropagation?" ever carry the Copenhagen-park anecdote about Seppo Linnainmaa, possibly before a post-2019 revision removed it? Two vault artifacts were opened directly (not assumed from the topic string) to confirm the answer and its destination:
10-inbox/raw/20260701-1650-did-schmidhubers-who-invented.md— the original research capture (2026-07-01) that did the actual Wayback/live-page work. Its frontmatter recordsstatus: promoted,promoted_to: "30-notes/claim-linnainmaa-copenhagen-anecdote.md (finding already absorbed there at cycle 1 — point 3 ... descends from this capture's resolution trail; no new note)". The capture directly fetched the live Schmidhuber page and a Wayback snapshot dated 2019-06-14, plus corroborating snapshots from 2014-10-25, 2016-01-02, 2024-12-25, and 2026-06-22 (the last four reported by a research subagent, flagged[unverified — subagent-reported, method-consistent but not independently re-fetched by primary agent]). None of the checked versions contain the word "Copenhagen." The two directly-verified data points (live page and the 2019-06-14 snapshot) are Tier 1 — Schmidhuber's own words, fetched via a transparent relay to the primary URL.30-notes/claim-linnainmaa-copenhagen-anecdote.md— the promoted claim note, point 3: "The anecdote is absent from Schmidhuber's page — Wayback snapshots from 2014–2026 never show it there (see the question-verify-griewank-2012-linnainmaa resolution trail). It belongs to Griewank 2012 alone; retellings that attribute it elsewhere are citing a citation." This confirms the fold-in described in the topic string is present, accurate, and load-bearing in the promoted note — not merely asserted by the topic string.50-questions/_answered/question-verify-griewank-2012-linnainmaa.md— the governing question,status: answered, withflags_to_resolveentries dated 2026-07-06 that trace the anecdote's confirmed primary home to Griewank's 2012 paper (verified verbatim, p. 389), consistent with the "absent from Schmidhuber, belongs to Griewank" conclusion.
Claim type: historical (a negative/absence claim about what a specific web page has and has not contained over time) — load-bearing enough (it forecloses a "post-2019 revision" premise) that the original 2026-07-01 capture treated it at Tier 1-2 rigor rather than resting on Tier 3-4 secondary retellings. Sourcing floor: Tier 3-4 acceptable for uncontested historical claims, escalating to Tier 1-2 for contested/surprising ones — met and exceeded; the original capture used direct Tier 1 primary-source fetches (live page + specific Wayback snapshot) for the two most load-bearing data points.
| Field | Value |
|---|---|
| source_title | "Who Invented Backpropagation?" |
| source_author | Jürgen Schmidhuber |
| source_url (live) | https://people.idsia.ch/~juergen/who-invented-backpropagation.html |
| source_url (2019-06-14 Wayback snapshot) | https://web.archive.org/web/20190614211621/https://people.idsia.ch/~juergen/who-invented-backpropagation.html |
| source_tier | 1 |
| exact_quote (live page, 2026-07-01 fetch) | "Explicit, efficient error backpropagation (BP) in arbitrary, discrete, possibly sparsely connected, NN-like networks was first described in a 1970 master's thesis (Linnainmaa, 1970, 1976)" |
| exact_quote (2019-06-14 snapshot) | "Explicit, efficient error backpropagation (BP) in arbitrary, discrete, possibly sparsely connected, NN-like networks apparently was first described in a 1970 master's thesis (Linnainmaa, 1970, 1976), albeit without reference to NNs." |
| negative finding | "The word 'Copenhagen' does not appear anywhere in the returned page text" (stated identically for both the live page and the 2019-06-14 snapshot) |
Neither 30-notes/claim-linnainmaa-copenhagen-anecdote.md nor 50-questions/_answered/question-verify-griewank-2012-linnainmaa.md required a correction as part of this dedupe check — the fold-in described in the topic string is accurate and already reflected in the promoted note, not merely asserted.
Why no further web research was performed
The original 2026-07-01 capture already cleared the sourcing floor for this claim type with direct fetches of the live page and a Wayback snapshot bracketing the "post-2019 revision" framing, plus a Tier 1 corroborating primary artifact (Schmidhuber's own 2014-07-22 CMU Connectionists mailing-list post, independently fetched and confirmed, also containing no Copenhagen reference). That capture was explicitly marked status: promoted with its finding folded into claim-linnainmaa-copenhagen-anecdote.md point 3 rather than spun out as a standalone note (per that capture's own not_promoted field: "Negative finding as standalone note — folded; a never-was-there claim doesn't warrant its own file when the host note carries it"). Re-running Wayback fetches a second time would not add new evidence; it would only re-confirm what a prior pass already confirmed at Tier 1. Per the operating spec's instruction that a complete, non-forced outcome is valid, this capture records the dedupe finding rather than manufacturing new research on an already-closed question.