Showing papers in "Theoretical Computer Science in 1981"

TL;DR: A general method for proving/deciding equivalences between omega-regular languages, whose recognizers are modified forms of Buchi or Muller-McNaughton automata, derived from Milner's notion of “simulation” is obtained.

TL;DR: To connect the abstract ideas of events and domains of information, it is shown how casual nets induce certain kinds of domains where the information points are certain sets of events, which allows translations between the languages of net theory and domain theory.

TL;DR: It is demonstrated that specification of the Temporal character of the program's behavior is absolutely essential for the unambiguous understanding of the meaning of programming constructs.

TL;DR: A linear-algebraic techniques for verifying invariant assertions are used, yielding a calculus of S-invariants for PrT-nets, and these modelling and analysis techniques are applied to a scheme for organizing a distributed data base taken from literature.

TL;DR: It is shown how Petri nets can be generalized to allow processes to be described by a common subnet, without losing the ability to distinguish between them.

TL;DR: It is shown that there is no effective procedure for determining whether or not two terms of the language of second-order logic have a common instance.

TL;DR: An algorithm is given and proved which reduces the computations of these zeros to the resolution of a single univariate equation which degree is the number of common zeros, which gives the whole algebraic and geometric structure of the set of zeros.

TL;DR: An elementary proof of the completeness of the Segerberg axions for Propositional Dynamic Logic is given.

TL;DR: A unified and general framework for the study of nondeterministic polynomial optimization problems (NPOP) is presented and some properties of NPOP's are investigated.

TL;DR: A precisely attainable lower bound on the succinctness of representing regular languages by boolean automata is shown; namely, it is shown that, for every n ⩾ 1, there exists a reduced automaton D n with n states such that the smallest boolean automaton accepting the same language has also n states.

TL;DR: The SCS problem is shown to be NP-complete for strings over an alphabet of size ⩾ 2 and the complexity of the Shortest Common Supersequence problem is considered.

TL;DR: As an application of the generalized product, the theorem of Brzozowski and Knast that the dot-depth hierarchy of star-free sets is infinite is proved.

TL;DR: Some hierarchies occurring through this systematic construction of increasingly complex ∗-varieties of congruences are shown to correspond to well-known hierarchies of monoids, thus indicating that this construction is natural from an algebraic point of view.

TL;DR: Two models of Random Access Machines suitable for sorting integers are presented and it is shown that a RAM with addition, subtraction, multiplication, and integer division can sort integers in the range of[0,2^{cn}] in O(n c + n) steps.

TL;DR: The model's primitivity and generality make it a suitable basis for cost comparison of distributed system implementations and potentially useful for design specification of systems and of subsystems.

TL;DR: It is shown that metric spaces with Polish topology can be represented very well by bounded complete ω-algebraic cpo's with continuous weight and distance with exact adequacy for describing the continuous functions on the corresponding metric spaces.

TL;DR: A number of simple tools are developed which facilitate the study of the structure of sets in NP and yield the existence of a minimal pair of sets A, S E NP which are not complete, which can be used to constru@ partial orders of degrees with respect to polynomial time reducibility.

TL;DR: The complexity L(A) of a finite dimensional associative algebra A is the number of non-scalar multiplications/divisions of an optimal algorithm to compute the product of two elements of the algebra, where t is theNumber of maximal two-sided ideals of A.

TL;DR: A method for algebraically structuring a compiler and proving it correct is described, which determines an initial many-sorted algebra L which is the ‘abstract syntax’ of the example language.

TL;DR: The power of these operations and their relation to the usual AFL-operations is studied and it is shown that flow expressions, event expressions and even very restricted variants of them define all the recursively enumerable sets.

TL;DR: A purely extensional (non operational) proof that no program passing the cycle sum test can ever deadlock is given, based on the notions of size (length) and completeness in the domain of histories, and should extend to a much wider context.

TL;DR: A unified approach to the presentation of concepts of semantics, correctness and termination in terms of Tarski's and Riguet's relational algebra is presented.

TL;DR: There is a polynomial time algorithm to determine whether a finite Thue system is Church-Rosser, and it is shown that this algorithm can be applied to solve the LaSalle inequality.

TL;DR: The number of pebbles used in the black [black-white] pebble game corresponds to the storage requirement of the deterministic [non-deterministic] evaluation of a straight line program.

TL;DR: The solution of the Firing Squad Synchronization Problem for graphs is given and the synchronization time is proportional to the radius rG of a graph, which is minimum for an infinite number of graphs.

TL;DR: The (best) upper and lower bounds on the subword complexity of infinite square-free DOL languages are established.

TL;DR: The NP() and NPQUERY() operators are studied in order to develop necessary and sufficient conditions for the class PSPACE to be equal to the union of the polynomial-time hierarchy.

TL;DR: It is shown that NP is equal to PSPACE if and only if for every oracle set A, NP( A ) isequal to the class NPQUERY ( A ) of languages accepted by nondeterministic polynomial space-bounded oracle machines that are allowed to query the oracle for A only aPolynomial number of times.

TL;DR: It is shown that if the limit of certain sequences of finite languages is of type X1 then the type X complexity of each of the finite languages involved must be low.

TL;DR: It is shown that no finite union of congruence classes [w], w being an arbitrary element of the free monoid {a, b}∗ with unit 1, is a context-free language if the congruent is defined by the single pair (abbaab, 1).