Massachusetts Institute of Technology
A. I. Laboratory
Artificial Intelligence Memo No. 239
February 29, 1972


M. Beeler []
R. W. Gosper []
R. Schroeppel []

[Retyped and formatted in 'html' ('Web browser format) by Henry Baker, April, 1995. The goal of this 'html' document is to make HAKMEM available to the widest possible audience -- including those without bitmapped graphics browsers. Therefore, equations have been formatted to be readable even on ASCII browsers such as 'lynx'. Click here to get original AI Memo 239 in 400 dots/inch, 1 bit/pixel, Group 4 facsimile TIFF format (a single 5 megabyte gzip compressed tar file, AIM-239.tiff.tar.gz).]

Work reported herein was conducted at the Artificial Intelligence Laboratory, a Massachusetts Institute of Technology research program supported in part by the Advanced Research Projects Agency of the Department of Defense and monitored by the Office of Naval Research under Contract Number N00014-70-A-0362-0002.

Reproduction of this document, in whole or in part, is permitted for any purpose of the United States Government.

Compiled with the hope that a record of the random things people do around here can save some duplication of effort -- except for fun.

Here is some little known data which may be of interest to computer hackers. The items and examples are so sketchy that to decipher them may require more sincerity and curiosity than a non-hacker can muster. Doubtless, little of this is new, but nowadays it's hard to tell. So we must be content to give you an insight, or save you some cycles, and to welcome further contributions of items, new or used.

The classification of items into sections is even more illogical than necessary. This is because later elaborations tend to shift perspective on many items, and this elaboration will (hopefully) continue after publication, since this text is retained in "machinable" form. We forgive in advance anyone deterred by this wretched typography.

People referred to are from the A. I. Lab:

Marvin Minsky        []
Bill Gosper          []
Michael Beeler       []
Joe Cohen
Jerry Freiberg
John Roe
Rich Schroeppel      []
David Silver
Michael Speciner
Richard Stallman     []
Gerald Sussman       []
David Waltz
Once at the A. I. Lab but now elsewhere:
Jan Kok                  William Henneman
Rici Liknaitzky          George Mitchell
Peter Samson             Stuart Nelson
Roger Banks              Rollo Silver
Mike Paterson
at Digital Equipment Corporation:
Jud Lenard               Dave Plumer
Ben Gurley (deceased)    Steve Root
elsewhere at M.I.T.:
Gene Salamin             PDP-1 hackers
Eric Jensen              Frances Yao
Edward Fredkin
once at M.I.T., but now elsewhere:
Jackson Wright           Steve Brown
Malcolm Rayfield
in France:
Marco Schutzenberger     Henry Cohen
at Computer Corporation of America:
Bill Mann
at BBN:
Robert Clements

Some of this material is very inside -- many readers will have to excuse cryptic references.

The label "PROBLEM" does not always mean exercise; if no solution is given, it means we couldn't solve it. If you solve a problem in here, let us know.

Unless otherwise stated, all computer programs are in PDP-6/10 assembly language.