Marianne Johnson

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math.GR2026

The endomorphism tower of a finite symmetric group

Victoria Gould, Ambroise Grau, Marianne Johnson +1

We consider the endomorphism tower of a monoid $M$ , that is, the sequence of monoids End $_{i} (M)$ where End $_{0} (M) = M$ and for all $i \geq 1$ , End $_{i} (M)$ is the monoid of all endomorphi…

math.GR2025

Free inverse monoids are co-context-free

Tara Macalister Brough, Marianne Johnson, Mark Kambites +1

We prove (using grammars) that the free inverse monoid of every finite rank has co-context-free word problem. Equivalently, the co-word problem of the free inverse monoid of every…