Character theory is a branch of abstract algebra that studies the properties of group representations through the use of characters, which are complex-valued functions defined on a group. It provides powerful tools for understanding the structure of groups, particularly finite groups, by analyzing how these groups can act on vector spaces.
The representation of algebras is a mathematical framework that studies modules over an algebra, focusing on how these modules can be decomposed and classified. It provides a bridge between abstract algebraic structures and linear algebra, allowing for the exploration of symmetry, structure, and transformations within algebraic systems.
The Peter-Weyl Theorem is a fundamental result in the representation theory of compact topological groups, which states that the space of square-integrable functions on such a group can be decomposed into an orthonormal basis of matrix coefficients of its irreducible unitary representations. This theorem provides a powerful tool for analyzing the structure of compact groups by linking their representation theory with harmonic analysis.
Linear representation refers to a way of representing group elements as matrices such that the group operation corresponds to matrix multiplication. This allows abstract group elements to be studied using linear algebra, providing powerful tools for analyzing symmetries and transformations in various mathematical and physical contexts.