Time-space tradeoffs for branching programs

We obtain the first non-trivial time-space tradeoff lower bound for functions f: {0,1}/sup n//spl rarr/{0,1} on general branching programs by exhibiting a Boolean function f that requires exponential size to be computed by any branching program of length (1+/spl epsiv/)n, for some constant /spl epsi...

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Bibliographic Details
Main Authors: Beame, P., Saks, M., Thathachar, J.S.
Format: Conference Proceeding
Language:English
Subjects:
Binary decision diagrams
Complexity theory
Computational modeling
Computer science
Input variables
Mathematics
Microwave integrated circuits
Pattern matching
Polynomials
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Summary:We obtain the first non-trivial time-space tradeoff lower bound for functions f: {0,1}/sup n//spl rarr/{0,1} on general branching programs by exhibiting a Boolean function f that requires exponential size to be computed by any branching program of length (1+/spl epsiv/)n, for some constant /spl epsiv/>0. We also give the first separation result between the syntactic and semantic read-k models for k>1 by showing that polynomial-size semantic read-twice branching programs can compute functions that require exponential size on any syntactic read-k branching program. We also show a time-space tradeoff result on the more general R-way branching program model: for any k, we give a function that requires exponential size to be computed by length kn q-way branching programs, for some q=q(k).
ISSN:0272-5428
DOI:10.1109/SFCS.1998.743453