Two matroids $M$ and $N$ are said to be concordant if there is a strong map from $M$. This also can stated by saying that each circuit of union circuits In this paper, we consider class called positroids, introduced Postnikov, utilize their combinatorics determine concordance among some them.
 More precisely, given uniform positroid, give purely combinatorial characterization family positr...

Let X be a Hausdorff quotient of standard space (that is locally compact separable metric space). It shown that the following are equivalent: (i) image an irreducible map from space; (ii) has sequentially dense subset satisfying two technical conditions involving double sequences; (iii) whenever q : Y → , restriction ⁎ | V onto (where pure derived and closure set singleton fibres ). The proof u...

In this paper, we propose a weak version of quotient for the algebraic action group on variety, which shall call pseudo-quotient. They arise when focus purely topological properties good Geometric Invariant Theory (GIT) quotients regardless their properties. The flexibility granted by nature enables an easier identification in geometric constructions than classical GIT quotients. We obtain seve...