Representation Gap of the Motzkin Monoid
Katharina Arms
TL;DR
The paper addresses the security risk posed by linear decomposition attacks in non-classical algebraic structures by analyzing the Motzkin monoid via cellular methods. It introduces and leverages Green's cell theory and Gram-matrix techniques to bound the dimensions of simple and semisimple representations, proving an exponential growth of the representation gap with base $3$. By truncating to submonoids based on the number of through strands and examining idempotent diagrams and faithfulness, it shows that both semisimple and simple gaps scale as $ heta(n^{-3/2} 3^n)$ while maintaining favorable gap ratios. These results position the Motzkin monoid as a promising candidate for cryptographic constructions resilient to linear-decomposition attacks, linking diagrammatic topology with finite monoid representation theory and potentially impacting quantum-topological contexts.
Abstract
The linear decomposition attack reveals a vulnerability in encryption algorithms operating within groups or monoids with excessively small representations. The representation gap, defined as the size of the smallest non-trivial representation, therefore serves as a metric to assess the security of these algorithms. This paper will demonstrate that the diagrammatic Motzkin monoids exhibit a large representation gap, positioning them as promising candidates for robust encryption algorithms.
