Replication and load-balancing are two fundamental techniques for improving availability and performance of distributed systems. However, correct and efficient realization of these techniques is intricate when the distributed environment may partition and merge because of processor and communication failures. In this thesis, we show how a view-synchronous group communication service recently sp...

The 2-way quantum finite automaton introduced by Kondacs and Watrous[KW97] can accept non-regular languages with bounded error in polynomial time. If we restrict the head of the automaton to moving classically and to moving only in one direction, the acceptance power of this 1-way quantum finite automaton is reduced to a proper subset of the regular languages. In this paper we study two differe...

For a given reachable automaton A, we prove that the (state-)endomorphism monoid End(A) divides its characteristic monoid M(A). Hence so does its (state-)automorphism group Aut(A), and, for finite A, Aut(A) is a homomorphic image of a subgroup of the characteristic monoid. It follows that in the presence of a (state-) automorphism group G of A, a finite automaton A (and its transformation monoi...

Some results from Dassow and Mitrana (Internat. J. Comput. Algebra (2000)), Griebach (Theoret. Comput. Sci. 7 (1978) 311) and Ibarra et al. (Theoret. Comput. Sci. 2 (1976) 271) are generalized for finite autómata over arbitrary groups. The closure properties of these autómata are poorer and the accepting power is smaller when abelian groups are considered. We prove that the addition of any abel...

In this paper, we extend the notion of (word) derivatives and partial due to (respectively) Brzozowski Antimirov tree using already known inductive formulae quotients. We define a new family extended regular expressions (using negation or intersection operators), show how compute Brzozowski-like automaton; fixed point construction, when it exists, is derivative automaton. Such deterministic aut...

This paper presents two specifications of causal group multicast. In the first, causal ordering will be explained and explored in the context of group multicast. Failures will be introduced and a specification of causal group multicast which includes node crashes will be given. This final specification describes the service provided by ISIS’s causal multicast facility. The models are expressed ...

This paper presents two specifications of causal group multicast. In the first, causal ordering will be explained and explored in the context of group multicast. Failures will be introduced and a specification of causal group multicast which includes node crashes will be given. This final specification describes the service provided by ISIS’s causal multicast facility. The models are expressed ...

due to the algorithmic simplicity, cellular automata (ca) models are useful and simple methods in structural optimization. in this paper, a cellular-automaton-based algorithm is presented for simultaneous shape and topology optimization of continuum structures, using five-step optimization procedure. two objective functions are considered and the optimization process is converted to the single ...

In this paper, at first we define the concepts of response function and accessible states of a complete residuated lattice-valued (for simplicity we write $mathcal{L}$-valued) tree automaton with a threshold $c.$ Then, related to these concepts, we prove some lemmas and theorems that are applied in considering some decision problems such as finiteness-value and emptiness-value of recognizable t...