中文

Defect Spaces and Gram Operators for Tensor-Valued Incidence Maps

组合数学 2026-05-28 v1

摘要

We study vector-valued incidence maps obtained from ordinary graph incidence maps by linear observation of the free vertex space. Let F\mathbb{F} be a field, D=(X,E,s,t)D = (X, E, s, t) a finite directed multigraph, UU an F\mathbb{F}-vector space, and ϕ:XU\phi : X \to U a vertex labeling with F\mathbb{F}-linear extension ϕ^:FXU\hat{\phi} : \mathbb{F}^X \to U. The vector-valued incidence map ϕ:FEU\partial_\phi : \mathbb{F}^E \to U, ϕ(1e)=ϕ(t(e))ϕ(s(e))\partial_\phi(\mathbf{1}_e) = \phi(t(e)) - \phi(s(e)), factors as ϕ=ϕ^BD\partial_\phi = \hat{\phi} \circ B_D, where BDB_D is the classical incidence map of DD. We prove the formula dimFKer(ϕ)=EX+c(D)+δϕ,\dim_{\mathbb{F}} \mathrm{Ker}(\partial_\phi) = |E| - |X| + c(D) + \delta_\phi, where c(D)c(D) is the number of weakly connected components of DD and δϕ:=dimF(Im(BD)Ker(ϕ^))\delta_\phi := \dim_{\mathbb{F}}(\mathrm{Im}(B_D) \cap \mathrm{Ker}(\hat{\phi})) is the defect invariant. We apply this framework to directed tensor-labeled hypergraphs H=(Q0,Q1,β)\mathcal{H} = (Q_0, Q_1, \beta), in which each hyperedge carries a pair of boundary tensors (Ae,Be)(A_e, B_e) in the tensor algebra T(FQ0)T(\mathbb{F}^{Q_0}), and prove that δ(H)=0\delta(\mathcal{H}) = 0 over any field for each of the six standard constructions, including symmetric encodings that degenerate in positive characteristic. Over F=R\mathbb{F} = \mathbb{R}, the edge Gram operator L=ββ\mathcal{L} = \partial_\beta^* \partial_\beta has rank Vmacrocmacroδ(H)|V_{\mathrm{macro}}| - c_{\mathrm{macro}} - \delta(\mathcal{H}), and its degree-truncated operators form a Loewner-monotone filtration whose rank increments equal the decrements of the defect filtration. We further realize the cycle space of every oriented hypergraph (in the sense of Reff--Rusnak) as Ker(β)\mathrm{Ker}(\partial_\beta) within this framework, and exhibit a four-edge inclusion--exclusion example with δ(H)=1\delta(\mathcal{H}) = 1.

引用

@article{arxiv.2605.28535,
  title  = {Defect Spaces and Gram Operators for Tensor-Valued Incidence Maps},
  author = {Kengo Miyamoto},
  journal= {arXiv preprint arXiv:2605.28535},
  year   = {2026}
}

备注

26 pages