Title
Small-space analogues of Valiant's classes
Abstract
In the uniform circuit model of computation, the width of a boolean circuit exactly characterises the "space" complexity of the computed function. Looking for a similar relationship in Valiant's algebraic model of computation, we propose width of an arithmetic circuit as a possible measure of space. We introduce the class VL as an algebraic variant of deterministic log-space L. In the uniform setting, we show that our definition coincides with that of VPSPACE at polynomial width. Further, todefinealgebraicvariants ofnon-deterministic space-bounded classes, we introduce the notion of "read-once" certificates for arithmetic circuits. We show that polynomial-size algebraic branching programs can be expressed as a read-once exponential sum over polynomials in VL, i.e. VBP ∈ ΣR ċ VL. We also show that ΣR ċ VBP = VBP, i.e. VBPs are stable under read-once exponential sums. Further, we show that read-once exponential sumsover a restricted class of constant-width arithmetic circuits are within VQP, and this is the largest known such subclass of poly-log-width circuits with this property.
Year
DOI
Venue
2009
10.1007/978-3-642-03409-1_23
FCT
Keywords
Field
DocType
arithmetic circuit,read-once exponential sum,read-once exponential sumsover,boolean circuit,algebraic variant,polynomial width,algebraic model,poly-log-width circuit,small-space analogue,constant-width arithmetic circuit,class vl,boolean circuits,model of computation,exponential sum,branching program,space complexity
Discrete mathematics,Combinatorics,Boolean circuit,Algebraic number,Circuit complexity,Exponential sum,Polynomial,PSPACE,Model of computation,Arithmetic circuit complexity,Mathematics
Conference
Volume
ISSN
ISBN
5699
0302-9743
3-642-03408-X
Citations 
PageRank 
References 
8
0.56
14
Authors
2
Name
Order
Citations
PageRank
Meena Mahajan168856.90
B. V. Raghavendra Rao25313.86