English

Planar spider theorem and asymmetric Frobenius algebras

Quantum Algebra 2021-11-29 v2

Abstract

The `spider theorem' for a general Frobenius algebra AA, classifies all maps AmAnA^{\otimes m}\to A^{\otimes n} that are built from the operations and, in a graphical representation, represented by a {\it connected} diagram. Here the algebra can be noncommutative and the Frobenius form can be asymmetric. We view this theorem as reducing any connected diagram to a standard form with jj beads BB, where jj is the number of bounded connected components of the original diagram. We study the associated F-dimension Hilbert series dimx=j=0xjdimj\dim_x=\sum_{j=0}^\infty x^j\dim_j, where dimj=ϵBj1\dim_j=\epsilon\circ B^j\circ 1 are invariants of the Frobenius structure. We also study moduli of asymmetric quasispecial and `weakly symmetric' Frobenius structures and their F-dimensions. Examples include general Frobenius structures on matrix algebras A=Md(k)A=M_d(k) and on group algebras kGk G as well as on uq(sl2)u_q(sl_2) at low roots of unity.

Keywords

Cite

@article{arxiv.2109.12106,
  title  = {Planar spider theorem and asymmetric Frobenius algebras},
  author = {Shahn Majid and Konstanze Rietsch},
  journal= {arXiv preprint arXiv:2109.12106},
  year   = {2021}
}

Comments

20 pages ams latex, several pdf graphics; significantly extended to include u_q(sl_2) and higher F-dimensions