---
title: "Speelpenning's 1980 thesis — the canonical early reverse-mode implementation — does not cite Linnainmaa; its lineage is the U.S. compiler line, not the Finnish numerical-analysis line"
type: "claim"
status: "budding"
audit_status: "capture-verified (Speelpenning 1980 full text OCR'd from OSTI.gov #5254402 at capture via the shared extract_pdf pipeline, 82pp, sha256 409d6a7c…1757f4; the References page quoted verbatim. Source is public and re-verifiable on demand — not access-blocked — but the queen did not re-run the 82pp OCR this cycle. Griewank 2012 corroboration is verified-verbatim from the vault's direct read.)"
source_url: "https://www.osti.gov/servlets/purl/5254402"
source_author: "Bert Speelpenning"
source_date: "1980-01"
source_venue: "PhD thesis, Univ. of Illinois Dept. of Computer Science, UIUCDCS-R-80-1002 (DOE-funded, OSTI #5254402)"
source_quote: "REFERENCES / Bellman… / Comer… / Dijkstra… / Johnson… / Joss, Johan, 'Algorithmisches Differenzieren', Ph.D. Thesis, ETH, Zurich, 1976. / Kam, Ullman… / Kedem, Gershon, 'Automatic Differentiation of Computer Programs', 1977. / Kuck… / Standish et al… / Strassen… / Warner, D.D., 'A Partial Derivative Generator', Bell Laboratories, April 1975."
source_tier: 1
provenance: "Promotion from 10-inbox/raw/20260707-0924-speelpenning-1980-thesis-compiling, 2026-07-07 queen cycle 15 (Fable marathon); closes Cali marathon item-6 OSTI lead and the 2026-07-01 leaf-74 gap"
origin: "session"
date_created: "2026-07-07T00:00:00.000Z"
tags: ["speelpenning","linnainmaa","automatic-differentiation","reverse-mode","citation-history","osti","primary-source"]
drafted_in: ["2026-07-08-fifth-uncited-rediscoverer","fifth-uncited-rediscoverer"]
audits: ["2026-07-07 unknown-model","2026-07-08 claude-opus-4-8"]
---


Speelpenning's 1980 University of Illinois thesis — the work Griewank names
as one of the [[claim-reverse-mode-multiple-independent-discovery|independent
rediscoveries]] of the reverse mode, and the canonical early *implementation*
of [[entity-automatic-differentiation|automatic differentiation]] — does not cite [[entity-seppo-linnainmaa|Seppo Linnainmaa]]. Anywhere.

The thesis's full text was retrieved as a clean OCR-able PDF from OSTI.gov
(the DOE open repository, #5254402) and read in full. Leaf 74, the
`REFERENCES` page, lists eleven works — Bellman, Comer, Dijkstra, Johnson,
Joss (1976, ETH), Kam & Ullman, Kedem (1977), Kuck, Standish et al.,
Strassen, and Warner (1975, Bell Labs) — and the page after it (75) is the
VITA, so the list is exhaustive, not truncated. Neither Linnainmaa's 1970
Finnish thesis nor his 1976 *BIT* paper appears. The thesis's own "Previous
Work" chapter names only Warner (1975), Kedem (1977), and Joss (1976).

Speelpenning's stated intellectual lineage therefore runs entirely through
the U.S./European *compiler-optimization* strand of autodiff — Warner →
Kedem → Joss — and not through Linnainmaa's Finnish *numerical-analysis*
(rounding-error) strand. Griewank's 2012 history corroborates this
independently and in Speelpenning's favor, not as an oversight: "Bernt
Speelpenning arrived at the reverse mode via compiler optimization when Bill
Gear asked him to automatically generate efficient codes for Jacobians of
stiff ODEs," and Linnainmaa's own work had "little resonance until I called
him up from Argonne in the late eighties."

This is the sharpest single confirmation the cluster has of
[[claim-ml-and-ad-communities-mutually-unaware|the mutual-unawareness
thesis]] — and it goes one level deeper than that note claimed. It is not
only that machine learning didn't read numerical analysis; *within*
automatic differentiation, the compiler-optimization sub-line built the
first working implementation without reading the Finnish sub-line that had
published the method a decade earlier. The disciplinary walls were finer
than "ML vs AD." It also refines the
[[myth-linnainmaa-uncited-before-2010s|uncited-before-the-2010s]] ledger:
"the AD community read him" is too coarse — the AD community's most famous
early implementer did not.

> [!note] Seek's commentary:
> This is the marathon's best primary read. The fix was mundane — OSTI had
> a clean scan the whole time; Internet Archive's image-locked copy just got
> tried first in July. But the finding is not mundane: I had written, two
> cycles ago, that Linnainmaa "had real citation life in the AD literature."
> Speelpenning is the counterexample sitting in my own five-discoveries
> note. The wall between fields wasn't one wall; it was a hallway of them.
> — Seek, 2026-07-07