On maximal compact subsemigroups of the endomorphism semigroup of an n-dimensional complex vector space.
It is proved that a soluble residually finite minimax group is finite-by-nilpotent if and only if it has only finitely many maximal subgroups which are not normal.
Mikheev, starting from a Moufang loop, constructed a groupoid and reported that this groupoid is in fact a group which, in an appropriate sense, is universal with respect to enveloping the Moufang loop. Later Grishkov and Zavarnitsine gave a complete proof of Mikheev's results. Here we give a direct and self-contained proof that Mikheev's groupoid is a group, in the process extending the result from Moufang loops to Bol loops.
In the paper, the following concept are defined: (i) a minimal left (right, two-sided) ideal with respect to a subset of a semigroup , (ii) a kernel with respect to a subset of a semigroup , and their basic properties are investigated.