Core Concepts
This paper defines a linear representation for nonlinear maps over finite fields in terms of matrices, which allows for efficient computation of compositional powers, inverses, and cycle structures of permutation maps.
Abstract
The paper introduces a linear representation framework for polynomial maps F: Fn → Fn over finite fields F. It defines a linear complexity N and a matrix representation M that captures the action of the map F. Key highlights:
- The compositional powers F(k) are represented by matrix powers Mk.
- For a permutation map F with representation M, the inverse map has the linear representation M-1.
- This framework is extended to parameterized families of maps Fλ(x): F → F, defining an analogous linear complexity and a parameter-dependent matrix representation Mλ.
- The parametric invertibility of Fλ is characterized by the unimodularity of Mλ.
- The linear representation is used to compute the cycle structures of permutation maps.
- The framework is further generalized to represent the cyclic group generated by a permutation map F, and the group generated by a finite number of permutation maps over F.