IN REPLY REFER TO:

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
ELECTRONICS RESEARCH CENTER
CAMBRIDGE, MASSACHUSETTS 02139

cQD February 27, 1967
MAR ~6 1967

Dr. Joshua Lederberg
Dept. of Medicine
Stanford University
Stanford, California

Dear Dr. Lederberg:

Your and Dr. Grace's work on computer ennumeration and identifi-
cation of trees has greatly benefitted some of our development
of algorithms for identifying an optimum set of measurements

for multi-terminal networks. Could you send us reports on
recent work?

Enclosed are informal rough drafts of papers to be published.
67-622 "Combinatorial Algorithms for Computer-Oriented Fault
Identification in Multi-Terminal Devices. 66-633 Combinatorial
Analysis of Multi-Terminal Devices. Any comment or evaluation,

perhaps by one of your graduate students, would of course
be welcome.

There seems to be a need for interchange of information
among "combinatorial-oriented algorithm" writers. Do you
think the time is ripe for getting a few key people together.
Perhaps a one-week tutorial workshop rather than a one-day
"short paper" conference may be desirable.

Incidentally, I believe your report IRL-1036/NASA CR68896
DENDRAL-64 "Topology of Cyclic Graphs" might be of real
interest to the IEEE Transactions on System Science and Cybernetics.
Sincerely,
blsth (7

W. W. Happ, Chief
Design Criteria Branch

Enclosures: 2