Department of
Applied
Mathematics

Plabic graphs in physics

Jan Novák

Technical University of Liberec

Abstract

We will define decorated permutation, Le-diagram and plabic graph. We further introduce winding index and formal boundary measurements. The amplituhedron A_{n,k,m} is the image in the Grassmannian Gr_{k,k+m} of the totally nonnegative part of Gr_{k,n} under a linear map. It was introduced in 2013 in order to give a geometric basis for the computation in physics. We finally show the connection of the plabic graphs and Grassmannians. We suppose only elementary prerequisites from graph theory and no knowledge of physics is required.