Representation Theory

Please find linked

Group

  • Set closed under associative binary operation with identity and inverse element
  • Var
    • Page Zoom in or out, composition
    • Page scroll up or down, composition
    • Integers, addition
    • Rotation \(SO(3)\), composition
  • Relate Sigma Algebra

Graph

  • State, interaction
  • vertex, edge
  • Adjacency Matrix is symmetric, Diagonal matrix is mirror
  • Adjacency matrix composition counts walks on graph
  • Spectral Theorem identifies Real Symmetric Matrix to the Diagonal matrix: real eigenvalue, orthonormal eigenvector basis
  • Cycles on graph correspond to Eigenvalue

Classify Interaction

  • Quiver to RefDigraph isomorphic ColDigraph Category
  • (Gabriel) Quiver (Directed graph) is of finite type if and only if underlying graph is \(A_n or D_n or E_6 or E_7 or E_8\) Dynkin diagram, with indecomposable representation corresponding to positive root.