Abstract
We consider two group actions on -tuples of matrices with entries in the field . The first is simultaneous conjugation by and the second is the left-right action of . Let be the algebraic closure of the field . Recently, a polynomial time algorithm was found to decide whether lies in the Zariski closure of the -orbit of a given -tuple by Garg, Gurvits, Oliveira and Wigderson for the base field . An algorithm that also works for finite fields of large enough cardinality was given by Ivanyos, Qiao and Subrahmanyam. A more general problem is the orbit closure separation problem that asks whether the orbit closures of two given -tuples intersect. For the conjugation action of a polynomial time algorithm for orbit closure separation was given by Forbes and Shpilka in characteristic . Here, we give a polynomial time algorithm for the orbit closure separation problem for both the conjugation action of and the left-right action of in arbitrary characteristic. We also improve the known bounds for the degree of separating invariants in these cases.
Citation
Harm Derksen. Visu Makam. "Algorithms for orbit closure separation for invariants and semi-invariants of matrices." Algebra Number Theory 14 (10) 2791 - 2813, 2020. https://doi.org/10.2140/ant.2020.14.2791
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