|
Search: id:A071536
|
|
|
| A071536 |
|
Extensions to a semigroup of the (categorical) composition of arrows in the complete directed graph on n labeled nodes. |
|
+0
1
|
| |
|
|
OFFSET
|
0,3
|
|
|
COMMENT
|
Terms obtained, especially the 147, lend some support to the peculiar conjecture that the composition in any category can be extended to a total, associative operation, that is to a semigroup (not, of course, a monoid).
|
|
EXAMPLE
|
For n=2, arrows 0:0->0, 1:1->1, f:0->1, g:1->0, the self-dual solution (commutes with reversing arrows) has multiplication table (rows and columns indexed by 0, 1, f, g in order) with rows: 0 f f 0; g 1 1 g; 0 f f 0; g 1 1 g.
|
|
CROSSREFS
|
Sequence in context: A010266 A009491 A006845 this_sequence A094755 A152418 A113457
Adjacent sequences: A071533 A071534 A071535 this_sequence A071537 A071538 A071539
|
|
KEYWORD
|
hard,nonn,nice
|
|
AUTHOR
|
F. Lockwood Morris (lockwood(AT)ecs.syr.edu), May 29 2002
|
|
|
Search completed in 0.002 seconds
|
