2 papers
math.LO2010
On the isomorphism problem of concept algebras
Leonard Kwuida, Hajime Machida
Weakly dicomplemented lattices are bounded lattices equipped with two unary operations to encode a negation on {\it concepts}. They have been introduced to capture the equational t…
math.RA2005
The minimal clones above the permutations
Hajime Machida, Michael Pinsker
We determine the atoms of the interval of the clone lattice consisting of those clones which contain all permutations, on an infinite base set. This is equivalent to the descriptio…