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Showing papers in "Journal of Computer and System Sciences in 1975"


Journal ArticleDOI
TL;DR: It is shown that the problem of finding an optimal schedule for a set of jobs is NP-complete even in the following two restricted cases, tantamount to showing that the scheduling problems mentioned are intractable.

1,356 citations


Journal ArticleDOI
TL;DR: A tree generating system called a tree adjunct grammar is described and its formal properties are studied relating them to the tree generating systems of Brainerd and Rounds and to the recognizable sets and local sets discussed by Thatcher.

831 citations


Journal ArticleDOI
TL;DR: Two versions of the polynomial time-reducibility of Cook and Karp are defined, by means of Turing machines and by bounded-quantifier formulas, and they are shown to be complete for nondeterministic (deterministic) log n space.

375 citations


Journal ArticleDOI
TL;DR: An algorithm for general context-free recognition is given that requires less than n3 time asymptotically for input strings of length n.

349 citations


Journal ArticleDOI
TL;DR: A simple but general parallel programming language is considered, and a program simulating an elementary airline reservation system is given, and several properties of the program are demonstrated using the technique.

149 citations


Journal ArticleDOI
TL;DR: The equivalence problem for deterministic one-counter automata is shown to bedecidable and a corollary for schema theory is that equivalence is decidable for Ianov schemas with an auxiliary counter.

120 citations


Journal ArticleDOI
TL;DR: In an attempt to provide a unified theory of grammars, a model is introduced which has two components, a ''grammar form,'' which provides the general structure of the productions in the grammar form, and an ''interpretation'', which yields a specific grammar.

91 citations


Journal ArticleDOI
TL;DR: The principal result described in this paper is the equivalence of the following statements: every set accepted by a nondeterministic one-way two-head finite automaton can be acceptance by a deterministic two-way k-head infinite automaton.

75 citations


Journal ArticleDOI
TL;DR: Manna's theorem on (partial) correctness of programs is extended to programs with (parameterless) recursion to provide a characterization of recursion which is an alternative to the minimal fixed point characterization, and to clarify the relationship between partial and total correctness.

64 citations


Journal ArticleDOI
TL;DR: A minimal realization theory for discrete-time machines with structure in a suitable closed monoidal category is developed, and the concept of an X-module and an initial object theorem are especially important.

45 citations


Journal ArticleDOI
TL;DR: A theorem which establishes a hierarchy of contentless languages whose recognizers require at least log n space is given and any nontrivial processor can be transformed into a recognizer of a nonregular language in the same input alphabet and using exactly the same space.

Journal ArticleDOI
TL;DR: This paper treats the problem of designing a fault tolerant cellular space which simulates an arbitrary given cellular space in real time and states that the introduced coding method is useful for correcting errors occurring at most once in every K=5x5 rectangle.

Journal ArticleDOI
TL;DR: Any one counter language that is not nonterminal bounded must contain an infinite regular set; every generator of the family of one counter languages must contain a finite regular set.

Journal ArticleDOI
TL;DR: This work uses geometrical codings to design fault tolerant cellular automata which simulate given Cellular automata, and the concept of a group graph is introduced as a mathematical description of the cellular structure.

Journal ArticleDOI
TL;DR: It is shown that for unambiguous sets the notion of rationality is independent of the semiring over which representations are defined, and the undecidability of the rationality of probabilistic word functions is established.

Journal ArticleDOI
TL;DR: It is shown that the honest subrecursive classes are dense under the partial ordering of set inclusion and there exists a pair of incomparable honest sub Recursion classes such that the greatest lower bound of the pair is the smaller of the first two classes and the least upper bound is the larger of thefirst two classes.

Journal ArticleDOI
Barry K. Rosen1
TL;DR: This work assigns context-free grammars to recursion schemes in such a way that schemes are tree equivalent iff their Grammars generate the same language, and shows that this relation is also narrow enough to imply input-output equivalence.

Journal ArticleDOI
TL;DR: The family of all context-free languages and several of its subfamilies are shown to be uniformly erasable, which generalizes the well-known result that every context- free language can be recognized by a quasirealtime pushdown acceptor.


Journal ArticleDOI
TL;DR: The notion of reversibility, or backward determinism, for cellular automata is investigated, giving effective conditions for the third property of injectivity and surjectivity of the global transition function of a cellular automaton.

Journal ArticleDOI
TL;DR: By extracting the basic properties common to the automata appeared in existing literatures, a general formulation of automata with ?

Journal ArticleDOI
TL;DR: The relationships between the concepts of Garden-of-Eden configurations and restrictions, mutually erasable configurations, and injective parallel transformations are considered for the tessellation structure which is a model of a uniformly interconnected array of identical finite-state machines.

Journal ArticleDOI
TL;DR: A notation for dynamics of discrete systems is presented and static objects and relations between them which from time to time undergo sudden changes are described mathematically by relational structures and productions similar to productions of graph grammars.

Journal ArticleDOI
TL;DR: It is shown that languages in the least full AFL enclosing all E0L-languages are of tape-complexity (log n)^3, and the proof indicates in what respect context-independent developmental languages are ''more complex'' than context-free languages.

Journal ArticleDOI
TL;DR: Some properties of the class of L languages with interactions are investigated and is found to be not closed under most of the usually considered operations on languages.

Journal ArticleDOI
TL;DR: The paper shows how compiler correctness can be proved, provided that semanticsof the source language is defined by recursion on the definition of its syntax.

Journal ArticleDOI
TL;DR: It is shown that every cluster point of the sequence {x"j} constructed by the method is a stationary point and the rate of convergence is (n-q)-step superlinear.


Journal ArticleDOI
TL;DR: It is shown that for any real constants b>a>=0, multitape Turing machines operating in space L"1(n)=[bn^r] can accept more sets than those operating inspace L"2( n)=[an^ r] provided the number of work tapes and tape alphabet size are held fixed.

Journal ArticleDOI
TL;DR: It is proved that if ℒ is an AFL, then ℐ(ℒ) and Download : Download full-size image are full AFL and are closed under reversal.