

A354279


Number of regular elements in the semigroup of all binary relations on [n].


1




OFFSET

0,2


COMMENTS

Let S be a semigroup. An element A in S is regular iff A = A*B*A for some B in S. An element in the semigroup of all binary relations is regular iff its row space forms a distributive lattice under set inclusion.


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CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



