As in our previous study of NP, it is useful to identify those problems that capture the essence of PSPACE in that they are the “hardest” problems in that class. We can define a notion of PSPACE-completeness in a manner exactly analogous to NP-completeness: Definition 1 Language L′ is PSPACE-hard if for every L ∈ PSPACE it holds that L ≤p L′. Language L′ is PSPACE-complete if L′ ∈ PSPACE and L′...

This contribution treats the estimation of reachable states for time invariant hybrid systems. Using the framework provided by Willems’ behavioural systems theory, we suggest a method based on l-complete approximations, which can be realized by finite state machines. The approximating behaviour is a superset of the original behaviour. Hence, the estimate of reachable states based on an l-comple...

Let C be any complexity class closed under log-lin reductions. We show that all sets complete for C under 1-L reductions are polynomialtime isomorphic to each other. We also generalize the result to reductions computed by finite-crossing machines. As a corollary, we show that all sets complete for C under 2-way DFA reductions are polynomial-time isomorphic to each other.

Recently, scientists from The Craig J. Venter Institute reported construction of very long DNA molecules using a variety of experimental procedures adopting a number of working hypotheses. Finding a mathematical rule for generation of such a long sequence would revolutionize our thinking on various advanced areas of biology, viz. evolution of long DNA chains in chromosomes, reasons for existenc...

This is the first complete mitochondrial genome sequence for sunflower and the first complete mitochondrial genome for any member of Asteraceae, the largest plant family, which includes over 23,000 named species. The master circle is 300,945-bp long and includes 27 protein-coding sequences, 18 tRNAs, and the 26S, 5S, and 18S rRNAs.

This contribution deals with the synthesis of supervisory control for hybrid systems with discrete external signals. Such systems are in general neither l-complete nor representable by nite state machines. We nd the strongest l-complete approximation (abstraction) l for , represent it by a nite state machine , and investigate the control problem for the approximation. If a solution exists, we s...