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Summary: Meanders, Ramsey Theory and lower bounds for branching programs
Noga Alon+ *
+Dept. of Math., Tel Aviv University
Ramat Aviv, Tel Aviv, Israel and
Bell C01T111l. Re!=;eArch,Morristown, N.J. 07960
ABSTRACT
A novel technique for obtaining lower
bounds for the time versus space comp1exity
of certain functions in a general input
oblivious sequential model of computation
is developed. This is demonstrated by
studying the intrinsic complexity of the
following set equality problem SE(n,m):
Given a sequence x1 ,x2 ,· .· ,xn ' Yl'·· .'Yn
of 2n numbers of m bits each, decide
whether the sets (xl' ··· ,xnJ and
(Yl' ··· 'YnJ coincide. We show that for
any lOglOgn~m~~lOgn and any
1 ~~
tfal-camputation that solves SE(n,m)~~
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