Tensor Network Complexity of Multilinear Maps

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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54

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THEORY OF COMPUTING, Volume 18, pp. 1-54

Abstract

We study tensor networks as a model of arithmetic computation for evaluating multilinear maps.These capture any algorithm based on low-rank tensor decompositions, such as $O(n^{\omega+\epsilon})$ time matrix multiplication, and in addition many other algorithms such as $O(n \log n)$ time discrete Fourier transform and $O^*(2^n)$ time for computing the permanent of a matrix. However, tensor networks sometimes yield faster algorithms than thosethat follow from low-rank decompositions. For instance the fastest known $O(n^{(\omega +\epsilon)t})$ time algorithms for counting $3t$-cliques can be implemented with tensor networks, even though the underlying tensor has rank $n^{3t}$ for all $t \ge 2$.For counting homomorphisms of a general pattern graph $P$ into a host graph on $n$ vertices we obtain an upper bound of $O(n^{(\omega+\epsilon)\bw(P)/2})$ where $\bw(P)$ is the branchwidth of $P$. This essentially matches the bound for counting cliques, and yields small improvements over previous algorithms for many choices of $P$.

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| openaire: EC/H2020/748354/EU//NonnegativeRank

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Austrin, P, Kaski, P & Kubjas, K 2022, 'Tensor Network Complexity of Multilinear Maps', THEORY OF COMPUTING, vol. 18, 16, pp. 1-54. https://doi.org/10.4086/toc.2022.v018a016