On free subsemigroups.
On automorphisms of Weyl algebra
AK-invariant, some conjectures, examples and counterexamples
In my talk I am going to remind you what is the AK-invariant and give examples of its usefulness. I shall also discuss basic conjectures about this invariant and some positive and negative results related to these conjectures.
On groups rings which are not Ore domains.
On Some Family of Contractible Hypersurfaces in
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