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Browsing by Author "Ruskuc, Nik"
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A finitely presented monoid with a non-finitely generated group of units
Carvalho, Catarina; Ruskuc, Nik (2007-08)We exhibit an example of a monoid defined by finitely many generators and defining relations, the group of units of which is not finitely generated -
On finite presentability of Bruck-Reilly extensions of a monoid with respect to an endomorphism and its powers.
Carvalho, Catarina; Ruskuc, Nik (2007-09)Let M be a monoid and let θ be an endomorphism of M. We prove that if the Bruck–Reilly extension BR(M, θ) is finitely presented, then the Bruck–Reilly extension BR(M, θm) is also finitely presented for all m ⩾ 1 -
Presentations of Inverse Semigroups their Kernels and Extensions
Carvalho, Catarina; Gray, Robert; Ruskuc, Nik (2011)Let S be an inverse semigroup and let π:S→T be a surjective homomorphism with kernel K. We show how to obtain a presentation for K from a presentation for S, and vice versa. We then investigate the relationship between the ...