Lower bounds for non-commutative computation
STOC '91 Proceedings of the twenty-third annual ACM symposium on Theory of computing
A Monte-Carlo algorithm for estimating the permanent
SIAM Journal on Computing
Random Structures & Algorithms
Determinant: Old Algorithms, New Insights
SIAM Journal on Discrete Mathematics
Clifford algebras and approximating the permanent
Journal of Computer and System Sciences - STOC 2002
A polynomial-time approximation algorithm for the permanent of a matrix with nonnegative entries
Journal of the ACM (JACM)
On the hardness of the noncommutative determinant
Proceedings of the forty-second ACM symposium on Theory of computing
Exponential time complexity of the permanent and the Tutte polynomial
ICALP'10 Proceedings of the 37th international colloquium conference on Automata, languages and programming
Almost settling the hardness of noncommutative determinant
Proceedings of the forty-third annual ACM symposium on Theory of computing
Complexity of the cover polynomial
ICALP'07 Proceedings of the 34th international conference on Automata, Languages and Programming
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We consider the complexity of computing the determinant over arbitrary finite-dimensional algebras. We first consider the case that A is fixed. We obtain the following dichotomy: If A/rad A is noncommutative, then computing the determinant over A is hard. "Hard" here means #P-hard over fields of characteristic 0 and ModpP-hard over fields of characteristic p0. If A/ rad A is commutative and the underlying field is perfect, then we can compute the determinant over A in polynomial time. We also consider the case when A is part of the input. Here the hardness is closely related to the nilpotency index of the commutator ideal of A. The commutator ideal com(A) of A is the ideal generated by all elements of the form xy−yx with x,y∈A. We prove that if the nilpotency index of com(A) is linear in n, where n ×n is the format of the given matrix, then computing the determinant is hard. On the other hand, we show the following upper bound: Assume that there is an algebra B⊆A with B=A/ rad(A). (If the underlying field is perfect, then this is always true.) The center Z(A) of A is the set of all elements that commute with all other elements. It is a commutative subalgebra. We call an ideal J a complete ideal of noncommuting elements if B+Z(A)+J=A. If there is such a J with nilpotency index o(n/logn), then we can compute the determinant in subexponential time. Therefore, the determinant cannot be hard in this case, assuming the counting version of the exponential time hypothesis. Our results answer several open questions posed by Chien et al. [4].