Electrical Networks and Symplectic Invariants
Abstract
Consider a finite planar graph with positive real edge weights and designated boundary vertices, called nodes. Such a graph is called a circular planar electrical network. A grove is a spanning forest in which every component contains at least one node. The connected components of a grove determine a partition of the nodes. We relate weighted grove counts to invariant theory for the symplectic group. To a planar electrical network G, we associate an Sp(2n)-invariant tensor ZG. For Sp(2)=SL(2), we expand ZG in the Temperley--Lieb basis indexed by noncrossing matchings and relate its coefficients to the Kenyon--Wilson grove formulas. For Sp(4), we give reduction rules for superpositions of two groves and prove that the tensors indexed by $3$-noncrossing matchings form a basis of the space of Sp(4)-invariant tensors. The coefficients of ZG in this basis are weighted counts of reduced double groves, up to normalization.
Related
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BibTeX
@misc{kogan2026electrical,
title = {{Electrical Networks and Symplectic Invariants}},
author = {David Kogan},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.07539},
eprint = {2610.07539},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.07539},
}
RIS
TY - UNPB
TI - Electrical Networks and Symplectic Invariants
AU - David Kogan
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.07539
UR - https://arxiv.org/abs/2610.07539
AB - Consider a finite planar graph with positive real edge weights and designated boundary vertices, called nodes. Such a graph is called a circular planar electrical network. A grove is a spanning forest in which every component contains at least one node. The connected components of a grove determine a partition of the nodes. We relate weighted grove counts to invariant theory for the symplectic group. To a planar electrical network G, we associate an Sp(2n)-invariant tensor Z_G. For Sp(2)=SL(2), we expand Z_G in the Temperley--Lieb basis indexed by noncrossing matchings and relate its coefficients to the Kenyon--Wilson grove formulas. For Sp(4), we give reduction rules for superpositions of two groves and prove that the tensors indexed by $3$-noncrossing matchings form a basis of the space of Sp(4)-invariant tensors. The coefficients of Z_G in this basis are weighted counts of reduced double groves, up to normalization.
ER -