Stefan D. Bruda

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We show that all the problems solvable by a nondeterministic machine with logarithmic work space (NL) can be solved in real time by a parallel machine, no matter how tight the real-time constraints are. We also show that several other real-time problems are in effect solvable in nondeterministic logarithmic space once their real-time constraints are dropped(More)
Traditionally, interest in parallel computation centered around the speedup provided by parallel algorithms over their sequential counterparts. In this paper, we ask a di erent type of question: Can parallel computers, due to their speed, do more than simply speed up the solution to a problem? We show that for real-time optimization problems, a parallel(More)
The primary purpose of parallel computation is the fast execution of computational tasks that are too slow to perform sequentially. However, it was shown recently that a second equally important motivation for using parallel computers exists: Within the paradigm of real-time computation, some classes of problems have the property that a solution to a(More)
In recent years, the software engineering community has put considerable efforts into the design and development of component-based software system (CBSS) in order to manage the software increasing complexity and to maximize the reuse of code. This paper presents some of such efforts by investigating the improved measurement tools and techniques, i.e.,(More)
The formalism of well-behaved timed languages was proposed in [7] as a tool for modeling practical real-time applications. We use this formalism for modeling aspects from the areas of real-time database systems and ad hoc networks. We offer formulations for the recognition problem in real-time database systems and for the routing problem in ad hoc networks.(More)
Software systems are used widely in many applications where a bug in the system can cause large damage. To prove the correctness of the software system by finding the bugs is the most important and the most difficult task. In this paper, we review and discuss the current approaches for software analysis mainly on model checking and testing. Model checking(More)
The use of component-based software engineering (CBSE) is growing in popularity among the software engineering community and it has been successfully applied in many engineering domains. Component quality evaluations by adequate metrics are needed for large scale project. However, the software quality evaluation should also be performed on component(More)
We show that, for any positive integer n , there exists at least one timed ω -language L n which is accepted by a 2n -processor real-time algorithm using arbitrarily slow processors, but cannot be accepted by a (2n-1) -processor real-time algorithm. It follows therefore that real-time algorithms form an infinite hierarchy with respect to the number of(More)
In the data{accumulating paradigm, the input is an endless stream. A computation is considered to be nished when all the already received data are processed before another datum arrives. We study sorting algorithms in this paradigm. First, we consider the data arrival law as being polynomial in time. We prove the existence of an upper bound on the running(More)
Data-accumulating algorithms (d-algorithms for short), extensively studied in [12], work on an input considered as a virtually endless stream. The computation terminates when all the currently arrived data have been processed before another datum arrives. In this paper a finer characterization of the class of d-algorithms is given, and it is shown that this(More)