The complexity of tensor calculus
The complexity of tensor calculus
复制标题
张量微积分的复杂性
DOI:
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发表时间:
2000
期刊:
影响因子:
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通讯作者:
P. McKenzie
中科院分区:
文献类型:
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作者:
C. Damm;M. Holzer;P. McKenzie
AbstractTensor calculus over semirings is shown relevant to complexity
theory in unexpected ways. First, evaluating well-formed tensor
formulas with explicit tensor entries is shown complete for $igoplusP$, for NP,
and for #P as the semiring varies. Indeed the permanent of a matrix
is shown expressible as the value of a tensor formula in much the same
way that Berkowitz’s theorem expresses its determinant. Second, restricted
tensor formulas are shown to capture the classes LOGCFL and
NL, their parity counterparts $igoplusLOGCFL$ and $igoplusL$, and several other
counting classes. Finally, the known inclusions $NP/poly subseteq igoplusP/poly$, $LOGCFL/poly subseteq igoplusLOGCFL/poly$, and $NL/poly subseteq igoplusL/poly$, which
have scattered proofs in the literature (Valiant & Vazirani 1986; Gál
& Wigderson 1996), are shown to follow from the new characterizations
in a single blow. As an intermediate tool, we define and make use of the
natural notion of an algebraic Turing machine over a semiring $ mathcal{S}$.