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Karoline P. Null

Publications and source records attributed to Karoline P. Null.

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Understanding 3-manifolds in the context of permutations

We demonstrate how a 3-manifold, a Heegaard diagram, and a group presentation can each be interpreted as a pair of signed permutations in the symmetric group $S_d.$ We demonstrate the power of permutation data in programming and discuss an algorithm we have developed that takes the permutation data as input and determines whether the data represents a closed 3-manifold. We therefore have an invariant of groups, that is given any group presentation, we can determine if that fixed presentation presents a closed 3-manifold. (The proposed techniques begin with a pair of signed permutations and builds a finite group presentation. The finite group presentation results in a finite class of associated 3-manifolds. Notice that a negative answer only implies the fixed presentation does not result in a closed 3-manifold under this construction, but says nothing about an isomorphic form of the group presentation.)

math.GT

Sufficient Conditions for Recognizing a 3-manifold Group

In this work we ask when a group is a 3-manifold group, or more specifically, when does a group presentation come naturally from a Heegaard diagram for a 3-manifold? We will give some conditions for partial answers to this form of the Isomorphism Problem by addressing how the presentation associated to a diagram for a splitting is related to the fundamental group of a 3-manifold. In the process, we determine an invariant of groups (by way of group presentations) for how far such presentations are from 3-manifolds.

math.GT