Two lower bounds about singular subspaces

Two lower bounds on

The lower bounds on communication complexity measures of language generation by Parallel Communicating Grammar Systems (PCGS) are investigated. The rst result shows that there exists a language that can be generated by some dag-PCGS (PCGS with communication structures realizable by directed acyclic graphs) consisting of 3 grammars, but by no PCGS with tree communication structure. The second re...

Two Lower Bounds for BPA

Branching bisimilarity on normed Basic Process Algebra (BPA) was claimed to be EXPTIMEhard in previous papers without any explicit proof. Recently it is reminded by Jančar that the claim is not so dependable. In this paper, we develop a new complete proof for EXPTIMEhardness of branching bisimilarity on normed BPA. We also prove the associate regularity problem on normed BPA is PSPACE-hard and ...

Lower Bounds for Two - Level

Lower bounds for the condition numbers of the preconditioned systems are obtained for two-level additive Schwarz preconditioners for both second order and fourth order problems. They show that the known upper bounds are sharp in the case of a small overlap.

Lower Bounds for Two Call Control Problems

We present lower bounds for two call control scheduling problems. For the problem of scheduling innnite-duration calls deterministically without pre-emption on a linear array of processors, in which the goal is to use as many edges as possible, we show a 2 + 1 4:2 lower bound on the competitive ratio (where is the golden ratio). For the problem of scheduling innnite-duration calls on an edge of...

Some Lower Bounds for Estrada Index