letters to the editor
AWARDING ACM’S 2017 A.M. Turing Award to John Hennessy and David Pat- terson was richly deserved and long overdue, as de-
scribed by Neil Savage in his news sto-
ry “Rewarded for RISC” (June 2018).

RISC was a big step forward. In their acceptance speech, Patterson also graciously acknowledged the contemporary and independent invention of the RISC concepts by John Cocke, another Turing laureate, at IBM, as described by Radin. 1 Unfortunately, Cocke, who was the principal inventor but rarely published, was not included as an author, and it would have been good if Savage had mentioned his contribution.

It is noteworthy that RISC architectures depend on and emerged from optimizing compilers. So far as I can tell, all the RISC inventors had strong backgrounds in both architecture and compilers.

Reference

1. Radin, G. The 801 minicomputer. IBM Journal of Research & Development (1983), 237–246.

Fred Brooks, Chapel Hill, NC, USA

No Inconsistencies in Fundamental
First-Order Theories in Logic

Referring to Martin E. Hellman’s Turing Lecture article “Cybersecurity, Nuclear Security, Alan Turing, and Illogical Logic” (Dec. 2017), Carl Hewitt’s letter to the editor “Final Knowledge with

Hennessy and Patterson
on the Roots of RISC

DOI: 10.1145/3273019

It is noteworthy that
RISC architectures
depend on and
emerged from
optimizing compilers.

Certainty Is Unobtainable” (Feb. 2018)

included a number of misleading statements, the most important that: “ Meanwhile, Gödel’s results were based on first-order logic, but every moderately powerful first-order theory is inconsistent. Consequently, computer science is changing to use higher-order logic.” Computer science is based on logic, mostly first-order logic, and programmers make their coding decisions using logic every day. The most important results of logic (such as Kurt Gödel’s Incompleteness Theorems) are taught in theory courses and are the fundamentals on which computer science and software engineering are based. No inconsistencies have ever been found in any of the standard first-order theories used in logic, ranging from moderately powerful to very powerful, and none are believed to be inconsistent.

Harvey Friedman, Columbus, OH, USA, and Victor Marek, Lexington, KY, USA

Author Responds:

Powerful first-order theories of intelligent information systems are inconsistent because these systems are not compact, thus violating a fundamental principle of first-order theories. Meanwhile, the properties of self-proof of inferential completeness and formal consistency in higher-order mathematical theories are the opposite of incompleteness and the self-unprovability of consistency Gödel showed for first-order theories. Differing properties between higher-order and first-order theories are reconciled by Gödel’s “I’mUnprovable” proposition’s nonexistence in higher-order theories.

First-order theories are not foundational to computer science, which indeed relies on the opposite of Gödel’s results.

Carl Hewitt, Palo Alto, CA, USA

More Accurate Text Analysis
for Better Patient Outcomes

David Gefen et al.’s article “Identifying Patterns in Medical Records through

Computer Vision

February 4 – May 10, 2019

Organizing Committee:

Y. Amit, University of Chicago

R. Basri, Weizmann Institute

A. Berg, University of NC

T. Berg, University of NC

P. Felzenszwalb, Brown Univ.

B. Fux Svaiter, IMPA

S. Geman, Brown University

B. Gidas, Brown University

D. Jacobs, University of MD

O. Veksler, Univ of W. Ontario

Program Description:

Computer vision is an inter-disciplinary topic crossing boundaries between computer science, statistics, mathematics, engineering, and cognitive science. Research in computer vision involves the development and evaluation of computational methods for image analysis.