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Electronic Colloquium on Computational Complexity

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TR04-042 | 21st May 2004
Ran Raz

Multilinear-$NC_1$ $\ne$ Multilinear-$NC_2$

An arithmetic circuit or formula is multilinear if the polynomial
computed at each of its wires is multilinear.
We give an explicit example for a polynomial $f(x_1,...,x_n)$,
with coefficients in $\{0,1\}$, such that over any field:
1) $f$ can be computed by a polynomial-size multilinear circuit
of depth $O(\log^2 ... more >>>


TR04-041 | 18th May 2004
Michael Alekhnovich, Edward Hirsch, Dmitry Itsykson

Exponential lower bounds for the running time of DPLL algorithms on satisfiable formulas

DPLL (for Davis, Putnam, Logemann, and Loveland) algorithms form the largest family of contemporary algorithms for SAT (the propositional satisfiability problem) and are widely used in applications. The recursion trees of DPLL algorithm executions on unsatisfiable formulas are equivalent to tree-like resolution proofs. Therefore, lower bounds for tree-like resolution (which ... more >>>


TR04-040 | 4th May 2004
Venkatesan Guruswami, Alexander Vardy

Maximum-likelihood decoding of Reed-Solomon codes is NP-hard

Maximum-likelihood decoding is one of the central algorithmic
problems in coding theory. It has been known for over 25 years
that maximum-likelihood decoding of general linear codes is
NP-hard. Nevertheless, it was so far unknown whether maximum-
likelihood decoding remains hard for any specific family of
more >>>



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