Oesterreichische Studiengesellschaft fuer Kybernetik (OeSGK)
Schottengasse 3, A-1010 Wien
Tel.+43-1-53532810,5336112
-------------------------------------------------------------------------
VORTRAG
*******
Prof.Dr.George SPENCER-BROWN
London
Uncolourable Trivalent Graphs
-----------------------------
Plenary Lecture at the
13th European Meeting on Cybernetics and Systems Research
(EMCSR'96)
A 3-graph is said to be uncolourable if its links cannot be completely
coloured with just three colours so that similarly-coloured links do not
meet at any node. It is considered trivial if it is less than five-
connected, or if it can obviously be factored so that one of the factors
is a smaller nontrivial uncolourable graph.
Isaacs (Am Math Monthly, 73 (1975) 221-239) described an infinite class
of nontrivial uncolourable 3-graphs but was unable to answer the question
whether it accounts for all such graphs. The present communication
demonstrates a method of factorization that supplies an affirmative
answer to this question.
Zeit: Mittwoch, 10.April 1996, 9:00 Uhr pktl.
********
Ort: Hoersaal 47 im Hauptgebaeude der Universitaet Wien,
**************************************************
Dr.Karl Lueger-Ring 1, 1010 Wien 1.