Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I
Communications of the ACM, 1960 · paper · Computer science
Describes LISP, a programming system for symbolic expression processing built on recursively defined functions. It introduces conditional expressions, S-expressions and a universal function, and shows how the system is represented on the IBM 704.
Checked: PDF from www-formal.stanford.edu, fetched 4 Oct 2026. Page numbers are those of that PDF.
8 findings
Substance In the LABEL clause of eval, "cons [list [cadar [e]; car [e]; a]];" has a misplaced bracket: list gets three arguments and cons gets one. Point 5 (p.18) requires cons[list[cadar[e]; car[e]]; a].
- p. 17 Definition of eval, LABEL clause
cons [list [cadar [e]; car [e]; a]];
Judge's note: I read the p.17 image. The bracket sequence makes a the third element of list, gives cons a single argument, and leaves the enclosing eval[ unclosed. Point 5 on p.18 says the pair (f, (LABEL, f, E)) is put on the front of the list a, which needs cons[list[...; ...]; a]. Footnote 5 ('This version isn't quite right') is a general caveat. It does not identify or correct this bracket.
Second check: another model agreed
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Substance In the LAMBDA clause of eval, "append [pair [cadar [e]; evlis [cdr [e]; a]; a]]]" passes a as a third argument to the two-argument pair and gives append one argument. Point 6 requires append[pair[cadar[e]; evlis[cdr[e]; a]]; a].
- p. 17 Definition of eval, LAMBDA clause
append [pair [cadar [e]; evlis [cdr [e]; a]; a]]]
Judge's note: I read the p.17 image. pair[ closes only after '; a]', so it receives three arguments and append receives one. Point 6 on p.18 says the list of pairs is put on the front of a, which is append[pair[...]; a]. Footnote 5's general caveat does not correct this.
Second check: another model agreed
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Substance eval's atomic case is printed as "atom [e] → assoc [e; a];", which returns the paired expression unevaluated. Point 3 says "eval evaluates whatever is paired with it first on the list a", and the p.19 trace goes from eval[X; a] to eval[(QUOTE, (A·B)); a] to (A·B).
- p. 17 Definition of eval, first clause
atom [e] → assoc [e; a];
- p. 18 Explanation point 3
eval evaluates whatever is paired with it first on the list a
- p. 19 apply trace
= atom [eval [(QUOTE, (A·B)); a]]
- p. 20 Evaluation of (CAR, X)
the earlier computation of atom [eval [X; a]] = A,
Only the authors can say what is right here.
Judge's note: I read the definition on the p.17 image, point 3 on p.18 and the trace on p.19. Under the printed definition, eval[X; a] = assoc[X; a] = (QUOTE, (A·B)), and the trace would reach atom[(QUOTE, (A·B))], not atom[(A·B)]. Footnote 5 admits that the version 'isn't quite right' but does not say which form is intended. This cluster is about the definition versus the prose and trace. The 'atom[eval[X; a]] = A' wording in reviewer note 2 is judged under C025.
Second check: another model agreed
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Substance The trace says evlis[((CAR, X)); a] "then becomes list [list [QUOTE; A]] = ((QUOTE, A))". The printed definition evlis[m; a] = [null[m] → NIL; T → cons[eval[car[m]; a]; evlis[cdr[m]; a]]] gives cons[A; NIL] = (A), with no QUOTE wrapping.
- p. 20 apply trace
list [list [QUOTE; A]] = ((QUOTE, A)),
- p. 17 Definition of evlis
evlis[m; a] = [null[m] → NIL; T → cons[eval[car[m]; a]; evlis[cdr[m]; a]]]
Only the authors can say what is right here.
Judge's note: I read evlis on the p.17 image and the trace on p.20. evlis as defined applies eval to each element and adds no quoting; only appq quotes. The trace then goes on to eval[(φ, (QUOTE, A)); a], which is consistent with the quoted form, not the defined one. Footnote 5 does not say which version the example follows.
Second check: another model agreed
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Substance In the general flowchart formula on p.33, "φ[ξ] = [p1[ξ] → φ1[f1[ξ]]; · · ·; pn[ξ] → φn[ξ]]]", the last branch omits fn (it should be φn[fn[ξ]]) and carries a surplus ']'
- p. 33 Section 6, general formula
pn[ξ] → φn[ξ]]]
- p. 33 Section 6 equation for φ[ξ]
φ[ξ] = [p1[ξ] →φ1[f1[ξ]]; · · ·; pn[ξ] →φn[ξ]]]
Judge's note: Read the equation on the p.33 crop. The text defines f1,…,fn as the computations leading to β1,…,βn, and φi as the function for βi. Figure 6 shows fn between β and βn. The first clause is φ1[f1[ξ]], so by the same pattern the last should be φn[fn[ξ]]. Bracket count: the conditional opens once and 'φn[ξ]' needs one ']'. The printed ']]]' therefore has one closing bracket too many. That count fits φn[fn[ξ]]] with 'fn[' dropped.
Second check: another model agreed
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Reference or label Footnote 1 on p.2 reads only "reference Kleene"; no Kleene work appears in the five-item reference list (p.34).
- p. 2 Footnote 1
reference Kleene
Only the authors can say what is right here.
Judge's note: The crop of p.2 shows the footnote text '1reference Kleene'. A search of the text layer finds 'Kleene' only in this footnote. The reference list on p.34 has five entries: McCarthy, Newell & Shaw, Church, FORTRAN manual, Perlis & Samelson. The citation is unfinished and points to nothing in the reference list.
Second check: another model agreed
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Reference or label Wrong section pointer on p.29: "A variant of the function apply described in section 5f". apply is described in section 3f ("f. The Universal S-Function apply", p.16)
- p. 29 Section 4f, first sentence
the function apply described in section 5f
- p. 16 Section 3f heading
f. The Universal S-Function apply
- p. 29 4f Status of the LISP Programming System
A variant of the function apply described in section 5f
- p. 29 Section 4f
described in section 5f
Judge's note: Page 29 reads 'section 5f'. The text layer shows that section 3 ('Recursive Functions of Symbolic Expressions') contains subsection f, 'The Universal S-Function apply' (p.16 crop). Section 5 ('Another Formalism for Functions of Symbolic Expressions') has no lettered subsections. The paper's other pointers ('section 3d', 'section 4b') use the same numbering, so 5f is wrong.
Second check: another model agreed
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Wording Translation rule 4 is printed "(COND, (p∗1, e∗1), · · · , (p∗n · e∗n))"; the last clause uses a dot instead of a comma, which makes it a dotted pair rather than the two-element list used for the first clause.
- p. 15 Translation rule 4
(p∗n · e∗n))
Judge's note: The p.15 image shows a centred dot between p_n* and e_n*, against a comma in the (p_1*, e_1*) clause. The two forms are different S-expressions under the paper's own definitions.
Second check: another model agreed
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38 minor (typos and the like; most checked by the judge only)
Reference or label The text refers to "figure 1a or 1b" (p.22) and to "figure 1b"/"figure 1c" (p.23), but the three diagrams in Fig. 1 have no a/b/c labels
- p. 23 Fig. 1 and following text
as in figure 1b, but it is not permitted for a structure to have cycles, as in figure 1c
- p. 22 Section 4a
arranged as in figure 1a or 1b
- p. 23 Figure 1 and following text
as in figure 1c
Judge's note: Page 23 shows Fig. 1 as three unlabelled structures (top, bottom-left, bottom-right) under the single caption 'Fig. 1'. Figure 2 is referred to by part as well ('list structure a of figure 2', 'figure 2b'). The content lets a reader infer the mapping (the shared substructure is bottom-left, the cycle is bottom-right), but no label is printed, so this is a labelling defect.
Second check: another model agreed
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Wording "= car [(A·B)], where we took steps from the earlier computation of atom [eval [X; a]] = A," reads as asserting atom[eval[X; a]] = A. The earlier computation on p.19 gave eval[X; a] = (A·B) and atom[...] = F; the '= A' presumably continues the chain from car[(A·B)].
- p. 20 apply trace, evaluation of evlis
where we took steps from the earlier computation of atom [eval [X; a]] = A
- p. 19 apply trace
= atom [(A·B)],
- p. 17 Definition of eval, first clause
atom [e] → assoc [e; a];
- p. 18 Explanation item 3
eval evaluates whatever is paired with it first on the list a
Only the authors can say what is right here.
Judge's note: On the p.20 image, '= A,' follows 'atom [eval [X; a]]' with no separating comma. P.19 ends that computation with atom[(A·B)] = F. The likely intent is car[(A·B)] = A, with the clause about earlier steps inserted in the middle, so this is an ambiguity in wording, not a wrong derivation. Reviewer note 2's point about the eval definition is the same as C021 and is judged there.
Second check: another model agreed
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Wording Promised discussion is not given: "In general (we shall discuss an exception), the routine for a recursive function uses itself as a subroutine". No exception is discussed later in this Part I
- p. 29 Section 4e, second paragraph
In general (we shall discuss an exception), the routine for a recursive func-
Only the authors can say what is right here.
Judge's note: Searched the full text for 'exception'. The only other hit is unrelated ('Conditional expressions give no trouble except...'). Section 4e goes on to SAVE/UNSAVE, and 4f–7 do not return to the point. The discussion may have been meant for a later part; only the author can say.
Second check: another model agreed
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Typo In the worked evaluation of 2!, the third line is printed "2 · (1 = 0 → 1T → ·(1 − 1)!)"; it should read "2 · (1 = 0 → 1, T → 1 · (1 − 1)!)".
- p. 5 Evaluation of 2!, third line
2 · (1 = 0 → 1T → ·(1 − 1)!)
Judge's note: The p.5 image shows the line exactly as quoted: no comma after the first clause and no left operand before '·(1 − 1)!'. The lines before and after (n=2 and n=0) follow the pattern '(n = 0 → 1, T → n · (n − 1)!)'. The intended form is clear from context.
Second check: none (judge only)
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Typo Duplicated word: "We can can represent a list of arbitrary length" (p.9, Section 3a).
- p. 9 Section 3a
We can can represent a list
- p. 9 Section 3a
We can can represent a list of arbi-
- p. 9
or simpler S-expressions. We can can represent a list of
Judge's note: The p.9 crop shows 'We can can represent', with both words on the same line.
Second check: code check
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Typo Agreement error: "any S-expression that occur stand for themselves" (p.10, Section 3b).
- p. 10 Section 3b
any S-expression that occur stand for themselves
- p. 10 Section 3b, last sentence
any S-expression that occur stand
Judge's note: The p.10 image shows the sentence as quoted. The noun is singular, the verbs are plural, and the reflexive 'themselves' is plural too.
Second check: none (judge only)
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Typo In two numbered lists the first item is labelled with the letter "l." instead of "1.": "l. (m) stands for (m ·NIL)." (p.10) and "l. Writing a compiler to compile LISP programs" (p.22).
- p. 10 List abbreviation rules
l. (m) stands for
- p. 10 List-notation abbreviations, item 1
l. (m) stands for (m ·NIL).
- p. 22 Section 4, purposes list item 1
l. Writing a compiler to compile LISP programs
Judge's note: In both crops the first label is the letter-l glyph (no flag or serif like a numeral 1), followed by items numbered 2, 3, ...
Second check: none (judge only)
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Typo The cons example is printed "cons [X; A] = (X A)"; by the definition cons[e1; e2] = (e1 · e2) just given, the result should be (X · A).
- p. 11 Elementary function cons, examples
cons [X; A] = (X A)
Judge's note: The p.11 image shows '(X A)' with no dot, while the dots elsewhere on the same page (e.g. car [(X · A)] = X) render normally. The result is not well formed in the paper's notation.
Second check: none (judge only)
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Typo The second cons example is printed "cons [(X · A); Y ] = ((X · A)Y )"; by the definition it should be ((X · A) · Y).
- p. 11 Section 3c item 5 (cons)
cons [(X · A); Y ] = ((X · A)Y )
Judge's note: The crop shows '((X · A)Y)' with no dot between (X · A) and Y. Compare 'car [((X · A) · Y)]' a few lines above. This is a separate line from C007, so I kept it as a separate defect.
Second check: none (judge only)
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Typo First step of the ff trace: "ff[car[((A · B)C·)]]" should read ff[car[((A · B) · C)]].
- p. 12 ff trace, first step
ff[car[((A · B)C·)]]
- p. 12 ff trace, first line
((A · B)C·)
Judge's note: The p.12 crop shows '((A · B)C·)' in the first '=' line. The same argument appears as '((A · B) · C)' everywhere else in the trace, including the atom[...] part of that same line.
Second check: none (judge only)
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Typo List identity (ii) is printed "cdr[(ms, m2, · · · , mn)] = (m2, · · · , mn)" with subscript s; it should be m1.
- p. 13 List-notation identity (ii)
(ii) cdr[(ms, m2, · · · , mn)] = (m2, · · · , mn)
- p. 13 list notation identity (ii)
cdr[(ms, m2, · · ·, mn)]
- p. 13 (ii)
cdr[(ms, m2, · · ·, mn)] = (m2, · · · , mn)
Judge's note: The p.13 crop clearly shows the subscript 's' in m_s. Identities (i) and (iv) use m1, and 's' is not defined anywhere.
Second check: none (judge only)
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Typo The pair definition ends "pair[cdr[x]; cdr[y]]]": the bracket opening the conditional "[null[x]∧null[y] → ..." is never closed.
- p. 14 Definition of pair
pair[cdr[x]; cdr[y]]]
Judge's note: I counted the brackets in the crop. Four brackets are still open before the final group: the conditional, cons[, pair[ and cdr[ (list[...] is closed). The trailing ']]]' closes only cdr, pair and cons, so the conditional bracket stays open. append, among and sub2 on the same pages are balanced.
Second check: none (judge only)
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Typo The assoc definition "assoc[x; y] = eq[caar[y]; x] → cadar[y]; T → assoc[x; cdr[y]]]" lacks the opening '[' of its conditional expression, so the final ']' is unmatched.
- p. 15 Definition of assoc
assoc[x; y] = eq[caar[y]; x] → cadar[y]; T → assoc[x; cdr[y]]]
Judge's note: The p.15 crop shows the right-hand side starting directly with 'eq[' with no '['. The trailing ']]]' closes cdr and assoc and leaves one ']' with no partner. Compare sub2 on the same page, which opens with '['.
Second check: none (judge only)
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Typo The sublis definition ends "sublis[x; cdr[y]]]": the bracket opening the conditional "[atom[y] → ..." is never closed.
- p. 15 Definition of sublis
sublis[x; cdr[y]]]
Judge's note: Counted in the crop: the brackets open at the end are the conditional, cons[, sublis[ and cdr[. The trailing ']]]' closes cdr, sublis and cons, leaving the conditional open. sub2 directly above is balanced.
Second check: none (judge only)
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Typo Wrong word: "the following rules in rich we denote the translation" should be "in which" (p.15, Section 3e).
- p. 15 Section 3e
the following rules in rich we denote
- p. 15 Section 3e
in rules in rich we denote
Judge's note: The p.15 image shows 'rules in rich we denote'. The second quoted variant ('in rules in rich') is not in the text, but the defect is the same.
Second check: none (judge only)
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Typo Translation rule 3 prints "(f∗, e∗1 · · ·, e∗n)" with no comma after e∗1; the comma-list form (f∗, e∗1, · · ·, e∗n) is meant.
- p. 15 Translation rule 3
(f∗, e∗1 · · ·, e∗n)
Judge's note: I checked the p.15 image. Rule 3 reads (f*, e1* ··· , en*). The example on the same line, (CONS, (CAR, X), (CDR, X)), separates every element with a comma.
Second check: none (judge only)
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Typo In the subst S-expression, the first clause of the inner conditional lacks its opening parenthesis: "(COND, (EQ, Y, Z), X), ((QUOTE, T), Z)))". Rule 4 gives (COND, ((EQ, Y, Z), X), ((QUOTE, T), Z)), and as printed the expression has one more ')' than '('.
- p. 16 S-expression translation of subst
(COND, (EQ, Y, Z), X), ((QUOTE, T), Z)))
- p. 16 S-expression translation of subst
(COND ((ATOM, Z), (COND, (EQ, Y, Z), X), ((QUOTE, T), Z)))
Judge's note: I counted the parentheses on the p.16 image and in the text layer. The depth after '(CDR, Z' is 6 and seven ')' follow, so the count ends at -1. The inner COND also closes after X, which leaves ((QUOTE, T), Z) outside it. Inserting '(' before (EQ, Y, Z) balances the expression and matches rule 4. The missing commas are a separate point, judged under C018.
Second check: none (judge only)
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Typo Two commas are missing from the subst S-expression: "(COND ((ATOM, Z)" and "(CAR Z))". The comma notation calls for (COND, ((ATOM, Z) ... and (CAR, Z).
- p. 16 S-expression translation of subst
(CAR Z))
Judge's note: On the p.16 image, the same expression writes (CDR, Z) with a comma and (CAR Z) without one, and (COND has no comma after it. Rule 4 on p.15 prints (COND, ...). This is a different defect from the missing parenthesis in C017.
Second check: none (judge only)
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Typo Point 6 prints the list of pairs as "((x1, e1), · · · , ((xn, en))" with an extra opening parenthesis; ((x1, e1), · · · , (xn, en)) is meant.
- p. 18 Point 6
((x1, e1), · · · , ((xn, en))
Judge's note: The p.18 image shows the doubled '((' before xn.
Second check: none (judge only)
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Typo The ff S-expression in the apply illustration prints "(COND, (ATOM, X), X), ((QUOTE, T),(FF, (CAR, X))))))". The first clause lacks its opening parenthesis, so the parentheses do not balance; (COND, ((ATOM, X), X), ((QUOTE, T), (FF, (CAR, X)))) is meant.
- p. 19 apply example
(COND, (ATOM, X), X), ((QUOTE, T),(FF, (CAR, X))))))
Judge's note: I counted on the p.19 image and in the text layer. The depth after '(CAR, X' is 5 and six ')' follow, so the count ends at -1. The COND closes right after the first X. The trace that follows treats it as (COND, (π1, ε1), (π2, ε2)).
Second check: none (judge only)
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Typo Misspelling: "Our main calulation continues with" should read 'calculation'.
- p. 19 End of page
Our main calulation continues with
Judge's note: The p.19 image shows 'calulation'. The word is spelled correctly on p.20.
Second check: none (judge only)
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Typo Stray comma in "= evcon [((π2, ϵ2, )); a],"; ((π2, ϵ2)) is meant.
- p. 20 apply trace
= evcon [((π2, ϵ2, )); a],
Judge's note: The p.20 image shows a trailing comma after ε2 inside the clause.
Second check: none (judge only)
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Typo In the M-expression trace, "= eval [Cons [φ; evlis [((CAR, X)); a]]; a]" capitalises the function name; lower-case 'cons' is meant.
- p. 20 apply trace
= eval [Cons [φ; evlis [((CAR, X)); a]]; a]
Judge's note: The p.20 image shows 'Cons'. Everywhere else, M-expression function names are lower case.
Second check: none (judge only)
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Typo The diff definition prints "eq [car [Y]; PLUS]" with an upper-case Y where the variable y is meant, as in 'eq[car [y]; TIMES]'.
- p. 21 Definition of diff
eq [car [Y]; PLUS]
Judge's note: The p.21 image shows car [Y] in the PLUS clause and car [y] in the TIMES clause. Under the paper's convention, upper-case letters denote S-expression constants.
Second check: none (judge only)
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Typo In diff's TIMES clause, "λ[[w]; ¬ eq [z; w] → car [w]; T → diff [car [[w]; x]]]]]]]" has the conditional's opening '[' missing before ¬ and an extra '[' in 'car [[w]'. [¬eq[z; w] → car[w]; T → diff[car[w]; x]] is meant.
- p. 21 Definition of diff, TIMES clause
T → diff [car [[w]; x]]]]]]]
- p. 21 Definition of diff, TIMES clause
λ[[w]; ¬ eq [z; w] → car [w]; T → diff [car [[w]; x]]]]]]]
Judge's note: The p.21 image shows the same bracket sequence as the text layer: no '[' opens the conditional inside the λ body, and car [[w] carries a spurious bracket. The bracket appears displaced, and the intended form is evident.
Second check: none (judge only)
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Typo Definition of search on p.21 lacks the closing bracket of its conditional: "search[x; p; f; u] = [null[x] → u; p[x] → f[x]; T → search[cdr[x]; p; f; u]"
- p. 21 Definition of search
T → search[cdr[x]; p; f; u]
Judge's note: Counted brackets on the page 21 image. The opening '[' before null[x] is never matched. Every inner bracket (null[x], p[x], f[x], cdr[x], search[...]) is closed, so one final ']' is missing. Compare maplist on the same page, which ends 'f]]]'.
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Typo The first item in the Section 4 list of purposes is numbered with the letter l: "l. Writing a compiler to compile LISP programs into machine language."; items 2–6 use digits
- p. 22 Section 4, list of purposes
l. Writing a compiler to compile LISP programs
Judge's note: The crop and page 22 show a lower-case 'l.' with a different glyph shape from the digits '2.'–'6.' that follow.
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Typo Capital letter mid-sentence on p.25: "The address part of each of these words points to a Word containing"
- p. 25 Section 4b, last line
points to a Word containing
Judge's note: The crop shows a capital 'W' in 'Word' mid-sentence, while 'words' is lower case in the same sentence.
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Typo On p.26 the machine name is printed with a letter O: "IBM 7O4 has a 36-bit word" (elsewhere "IBM 704")
- p. 26 Section 4b, parenthetical
IBM 7O4 has a 36-bit word
Judge's note: In the crop the middle character is a round capital O, visibly wider than the digit 0 in 'IBM 704' on page 22.
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Typo On p.29 a sentence begins in lower case: "by S-expressions. these functions may refer to each other"
- p. 29 Section 4f, feature 1
these functions may refer to each other
Judge's note: Page 29 image, feature 1: the new sentence after the full stop starts with a lower-case 'these'.
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Typo The definition of L-expressions on p.30 lacks its verb: "Any string of admitted characters in an L-expression." (should read "is an L-expression")
- p. 30 Section 5, definition of L-expressions
Any string of admitted characters in an L-expression.
Judge's note: The crop shows 'in an L-expression'. As printed the sentence has no main verb.
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Typo Misspelling on p.32: "We give as an example the flowcart of figure 5."
- p. 32 Section 6
We give as an example the flowcart of figure 5.
- p. 32 paragraph after Figure 5
flowcart of figure 5
Judge's note: Page 32 image shows 'flowcart'. The next paragraph spells 'flowchart' correctly.
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Typo One function is named two ways on p.32: the prose says "the functions s(ξ), and t[ξ]", but the equations use "S[ξ]"
- p. 32 Section 6, text and equations
the functions s(ξ),
- p. 32 Section 6, Figure 5 discussion
in conjunction with the functions s(ξ),
- p. 32 Equations for r, S, t
S[ξ]
- p. 32 Flowchart example
functions s(ξ),
Judge's note: Page 32 image: the prose has a lower-case s with parentheses. The defining equations use an upper-case italic S with brackets (S[f1[ξ]], S[ξ] = ...), while r and t are lower case. The meaning is recoverable because S is also the point label in Figure 5.
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Typo The predicate in the t[ξ] equation on p.32 is printed "[π3I[ξ] → f4[ξ];" with a capital I and an unsubscripted 3, where the pattern (π₁1, π₂1, π₃2) calls for π₃1
- p. 32 Equation for t[ξ]
[π3I[ξ] → f4[ξ];
- p. 32 Equation for t[ξ]
π3I[ξ]
- p. 32 equations for t[ξ]
π3I[ξ] → f4[ξ]; π32[ξ]
- p. 32 text before equations
functions s(ξ), and t[ξ]
Judge's note: The crop shows 'π3I' in italic: the 3 is full size, not a subscript, and the last character is a capital I. The parallel predicates are printed π₁1, π₂1 and π₃2.
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Typo In the Acknowledgments (p.33) LISP is printed with a lower-case l: "The LlSP programming system"
- p. 33 Acknowledgments
The LlSP programming system
Judge's note: In the crop the second letter is visibly a lower-case l with an ascender taller than the capitals, unlike the 'I' in 'IBM' on the line above.
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Typo Duplicated word across a line break in the Acknowledgments (p.33): "supported in part by the / the U.S. Army (Signal Corps)"
- p. 33 Acknowledgments
supported in part by the the U.S. Army
- p. 33
which is supported in part by the the U.S. Army (Signal C
Judge's note: The crop shows 'the' at the end of one line and again at the start of the next.
Second check: code check
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Typo Acknowledgments (p. 33) print the IBM co-inventor's name as "C. Gerberick and H. L. Gelernter"; the name is usually spelled Gerberich.
- p. 33 Acknowledgments
C. Gerberick and H. L. Gelernter
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: that the IBM researcher (Carl Gerberich, FLPL co-author with Gelernter) spells his name 'Gerberich'. The crop shows 'C. Gerberick and H. L. Gelernter, of IBM Corporation' exactly as quoted. Nothing in the files says how the name is spelled, so this is an author query about the spelling. The reviewer's side remark about 'H. L. Gelernter' cannot be checked from the files and is not confirmed.
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Typo Reference 5 prints the author's name as "A. J. PERLIS AND K. SAMELS0N", with the digit zero in place of the letter O (Samelson).
- p. 34 Reference 5
K. SAMELS0N
Judge's note: In the crop of p. 34, the character before the final N in 'SAMELS0N' is visibly narrower than the capital O in nearby words such as 'NEWELL' and 'CONVERSION'. That matches the digit 0, and the text layer also has '0', so this is not an extraction artefact. The fix is clear: change it to 'SAMELSON'.
Second check: none (judge only)