Signed dual graphs and face spectral gaps of Cayley 2-complexes
We construct a weighted signed dual multigraph for the Cayley $2$-complex of a finite presentation and represent its $\ell^2$ face Laplacian as a signed graph Laplacian with a diagonal potential. We prove that the face spectral gap above the kernel vanishes for the Baumslag--Solitar groups $\operatorname{BS}(1,m)$, $m\...