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Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

William & Mary

Mathematics

2021

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

Determining Quantum Symmetry In Graphs Using Planar Algebras, Akshata Pisharody May 2021

Determining Quantum Symmetry In Graphs Using Planar Algebras, Akshata Pisharody

Undergraduate Honors Theses

A graph has quantum symmetry if the algebra associated with its quantum automorphism group is non-commutative. We study what quantum symmetry means and outline one specific method for determining whether a graph has quantum symmetry, a method that involves studying planar algebras and manipulating planar tangles. Modifying a previously used method, we prove that the 5-cycle has no quantum symmetry by showing it has the generating property.


The Minimum Number Of Multiplicity 1 Eigenvalues Among Real Symmetric Matrices Whose Graph Is A Tree, Wenxuan Ding May 2021

The Minimum Number Of Multiplicity 1 Eigenvalues Among Real Symmetric Matrices Whose Graph Is A Tree, Wenxuan Ding

Undergraduate Honors Theses

For a tree T, U(T) denotes the minimum number of eigenvalues of multiplicity 1 among all real symmetric matrices whose graph is T. It is known that U(T) >= 2. A tree is linear if all its vertices of degree at least 3 lie on a single induced path, and k-linear if there are k of these high degree vertices. If T′ is a linear tree resulting from the addition of 1 vertex to T, we show that |U(T′)−U(T)|


A Survey Of Methods To Determine Quantum Symmetry Of Graphs, Samantha Phillips May 2021

A Survey Of Methods To Determine Quantum Symmetry Of Graphs, Samantha Phillips

Undergraduate Honors Theses

We introduce the theory of quantum symmetry of a graph by starting with quantum permutation groups and classical automorphism groups. We study graphs with and without quantum symmetry to provide a comprehensive view of current techniques used to determine whether a graph has quantum symmetry. Methods provided include specific tools to show commutativity of generators of algebras of quantum automorphism groups of distance-transitive graphs; a theorem that describes why nontrivial, disjoint automorphisms in the automorphism group implies quantum symmetry; and a planar algebra approach to studying symmetry.