Showing papers in "Theoretical Computer Science in 1980"

TL;DR: When selecting from, or sorting, a file stored on a read-only tape and the internal storage is rather limited, several passes of the input tape may be required.

TL;DR: A one-one correspondence between all the regular binary trees with n internal nodes and certain integer sequences, an algorithm for generating these trees lexicographically, and the ranking function and the corresponding unranking procedure is shown.

TL;DR: It is shown that any system of equations of the form X i = ⋃ α∈A α·F i,a ∪δ i i=1,…,n has a unique solution which, moreover, is regular.

TL;DR: A method of encoding the computation of an alternating TM into a logical theory, using Ehrenfencht games, and the proof of a general theorem is outlined.

TL;DR: This work gives a general technique for determining the complexity of decidable combinations of theories, and shows that the satisfiability problem for the quantifier-free theory of integers, arrays, list structure and uninterpreted function symbols under +, ≤, store, select, cons, car and cdr is NP-complete.

TL;DR: It is shown that for any deterministic Turing machine which runs in space S (n) and which possibly rejects by looping, there is an equivalent Turing machineWhich runs in the same amount of space and always halts and which applies to other deterministic computation models.

TL;DR: The results show that the class of probability distributions on a cPO is itself a cpo and that every probability distribution is the lub of an increasing sequence of ‘finite’ probability distributions.

TL;DR: In this setting, the two main theorems of semantics of semantics are proved: equivalence between operational and denotational semantics and the one-many function computed by a program is the image of the set of trees computed by the program.

TL;DR: This work analyzes two recent probabilistic primality testing algorithms, derived from Miller in a formulation given by Rabin and Solovay and Strassen, and shows that the first algorithm is always more efficient than the second, both in Probabilistic and algorithmic terms.

TL;DR: It is shown that the average number of rebalancing operations (rotations and double rotations) in weight-balanced trees is constant.

TL;DR: The main result is that there exists an oracle set A such that PPA −(Π2P,A ∪ σ2 P,A) ≠ ∅, with the corollary that also D ≠PA − (Π 2P, a ∪σ2 p, A) ≦ ∅.

TL;DR: In this article, it was shown that an exponential speedup can be achieved using {+,−,×} rather than just {+,×} as operations for the problem of perfect matchings in planar graphs.

TL;DR: The behaviour of a system is defined as a set of processes which can be obtained by composing certain elementary processes, and which sets of processes are the behaviours of concurrent systems are explained.

TL;DR: The result is a theory akin to the axiomatic treatment of recursive function theory of Strong and Wagner, which proves results relating the complexity of uniform simulation, diagonalization, deciding membership, and deciding halting.

TL;DR: It is shown that the elementary theory of Boolean algebras is ⩽ log -complete for the Berman complexity class ⋃ c STA(∗, 2 cn , n ), the class of sets accepted by alternating Turing machines running in time 2 cm and making at most n alternations on inputs of length n ; thus the theory is computationally equivalent to the theory of real addition with order.

TL;DR: It is proved that such extensions always exist, and the construction of a free extension is given, and it is shown that in some cases there is no ‘faithful’ extension, i.e. some elements of a carrier are always collapsed.

TL;DR: A theory of graph-like expressions is developed as far as the basic theoretical result which underlies the remainder of the study of efficient evaluations of expressions, which shows that for a wide class of expressions there are theoretical benefits in allowing graph- like expressions in evaluation algorithms.

TL;DR: A notion of LP-completeness is introduced, a set of problems is shown to be (polynomially) equivalent to linear programming, and a transformation is given to produce NP-complete versions ofLP-complete provlems.

TL;DR: To compute the result of the composition of functions and to solve fixpoint equations, this work uses a special kind of network of parallel processes built up in a modular way and proves that every computable function is continuous.

TL;DR: In this paper, the authors compare the notions of strong NP-completeness and simple and rigid problems, and show that under reasonable hypothesis, p-simple problems are solved by pseudo-polynomial algorithms and strong NPcomplete problems are weakly rigid.

TL;DR: Polynomial time algorithms are presented which benefit from selective non-use of slow processors, and the techniques of analyzing these schedules are used to obtain a bound on a large class of preemptive schedules.

TL;DR: In this paper the assumption of sequential independence is dropped and the Concurrency Theorem is formulated and proved in the framework of the algebraic theory of graph grammars using new pushout and pullback lemmas for the 3- and 4- dimensional cubes.

TL;DR: A method is given, based on algebraic geometry, to show lower bounds for the complexity of polynomials with algebraic coefficients, and this is applied also to systems of linear equations.

TL;DR: This note shows how a set of n homogeneous monotone Boolean functions of the first degree in n variables that require ?

TL;DR: A new inference rule is introduced, the subset rule, and using this rule it is proved that a certain system is complete, and the role of the so-called complementation rule is clarified.

TL;DR: A nondeterministic control structure is added to a typed λ-calculus and the usual operational semantics for the deterministic language is generalized to take into account the more complex behaviour of nondetergetic algorithms.

TL;DR: An algorithm is given to determine the mode of a multiset in a number of comparisons differing from the lower bound by only a ‘lower order term’.

TL;DR: C ( f n ) is the minimal size of a Boolean network which computes f n over the base of all 16 binary Boolean operations, and this lower bound corresponds to an upper bound of 3 n provided that the authors count only those gates that depend on some variable z j.

TL;DR: A new lower bound on the computational complexity of the theory of real addition and several related theories is established: any decision procedure requires either space 2? n or nondeterministic time 2?n2 for some constant ?