Results 1  10
of
12
LambdaCalculus Schemata
, 1993
"... A lambdacalculus schema is an expression of the lambda calculus augmented by uninterpreted constant and operator symbols. It is an abstraction of programming languages such as LISP which permit functions to be passed to and returned from other functions. When given an interpretation for its constan ..."
Abstract

Cited by 101 (1 self)
 Add to MetaCart
A lambdacalculus schema is an expression of the lambda calculus augmented by uninterpreted constant and operator symbols. It is an abstraction of programming languages such as LISP which permit functions to be passed to and returned from other functions. When given an interpretation for its constant and operator symbols, certain schemata, called lambda abstractions, naturally define partial functions over the domain of interpretation. Two implementation strategies are considered: the retention strategy in which all variable bindings are retained until no longer needed (implying the use of some sort of garbagecollected store) and the deletion strategy, modeled after the usual stack implementation of ALGOL 60, in which variable bindings are destroyed when control leaves the procedure (or block) in which they were created. Not all lambda abstractions evaluate correctly under the deletion strategy. Nevertheless, both strategies are equally powerful in the sense that any lambda abstraction can be mechanically translated into another that evaluates correctly under the deletion strategy and defines the same partial function over the domain of interpretation as the original. Proof is by translation into continuationpassing style.
Conjunctive Grammars
"... This paper introduces a class of formal grammars made up by augmenting the formalism of contextfree grammars with an explicit settheoretic intersection operation. ..."
Abstract

Cited by 59 (33 self)
 Add to MetaCart
This paper introduces a class of formal grammars made up by augmenting the formalism of contextfree grammars with an explicit settheoretic intersection operation.
Petri Net Algorithms in the Theory of Matrix Grammars
 Acta Informatica
, 1994
"... This paper shows that the languages over a oneletter alphabet generated by a contextfree matrix grammar are always regular. Moreover we give a decision procedure for the question of whether a contextfree matrix language is finite. Hereby we strengthen a result of [Mk 92] and settle a number of op ..."
Abstract

Cited by 49 (0 self)
 Add to MetaCart
This paper shows that the languages over a oneletter alphabet generated by a contextfree matrix grammar are always regular. Moreover we give a decision procedure for the question of whether a contextfree matrix language is finite. Hereby we strengthen a result of [Mk 92] and settle a number of open questions in [DP 89]. Both results are obtained by a reduction to Petri net problems. 1 Introduction Petri nets and vector addition systems are different representations of the same construct. While their notation as nets emphasizes their role as a specification and analysis tool for distributed systems, their alternative definition as vector replacement systems illustrates their importance in the theory of formal languages. Here they are regarded as semiThue systems for commutative monoids over a finite alphabet in contrast to the usually considered free monoid. The alphabet is represented in the set of places, the transitions play the role of grammatical rules, and the actually derived...
A robust class of contextsensitive languages
 In LICS
, 2007
"... We define a new class of languages defined by multistack automata that forms a robust subclass of contextsensitive languages, with decidable emptiness and closure under boolean operations. This class, called multistack visibly pushdown languages (MVPLs), is defined using multistack pushdown auto ..."
Abstract

Cited by 25 (6 self)
 Add to MetaCart
We define a new class of languages defined by multistack automata that forms a robust subclass of contextsensitive languages, with decidable emptiness and closure under boolean operations. This class, called multistack visibly pushdown languages (MVPLs), is defined using multistack pushdown automata with two restrictions: (a) the pushdown automaton is visible, i.e. the input letter determines the operation on the stacks, and (b) any computation of the machine can be split into�stages, where in each stage, there is at most one stack that is popped. MVPLs are an extension of visibly pushdown languages that captures noncontext free behaviors, and has applications in analyzing abstractions of multithreaded recursive programs, significantly enlarging the search space that can be explored for them. We show that MVPLs are closed under boolean operations, and problems such as emptiness and inclusion are decidable. We characterize MVPLs using monadic secondorder logic over appropriate structures, and exhibit a Parikh theorem for them. 1.
Strong Generative Capacity, Weak Generative Capacity, and Modern Linguistic Theories
, 1984
"... this paper. The basic points to be made are these: Since modern transformational grammars do not contain the powerful deletion rules available in the Aspects theory and need not explicitly reconstruct an underlying deep structure, they are not immediately subject to the Peters and Ritchie results. ..."
Abstract

Cited by 4 (0 self)
 Add to MetaCart
this paper. The basic points to be made are these: Since modern transformational grammars do not contain the powerful deletion rules available in the Aspects theory and need not explicitly reconstruct an underlying deep structure, they are not immediately subject to the Peters and Ritchie results. Thus the fears recently advanced by Bresnan and Kaplan (1982: xlixlii) or JohnsonLaird (1983: 280) simply do not hold
Decidability of Code Properties
 Proc. 4th International Conference Developments in Language Theory, (G. Rozenberg, W. Thomas, Eds.) World Scientific
"... We explore the borderline between decidability and undecidability of the following question: "Let C be a class of codes. Given a machine M of type X, is it decidable whether the language L(M) lies in C or not?" for codes in general, !codes, codes of finite and bounded deciphering delay, prefix, ..."
Abstract

Cited by 3 (2 self)
 Add to MetaCart
We explore the borderline between decidability and undecidability of the following question: "Let C be a class of codes. Given a machine M of type X, is it decidable whether the language L(M) lies in C or not?" for codes in general, !codes, codes of finite and bounded deciphering delay, prefix, suffix and bi(pre)fix codes, and for finite automata equipped with different versions of pushdown stores and counters.
FlipPushdown Automata: Nondeterminism is Better than Determinism
 IFIG Research Report 0301 ¡ ¢ FlipPushdown Automata – p.16/16
, 2003
"... Flippushdown automata are pushdown automata with the additional ability to ip or reverse its pushdown. We investigate deterministic and nondeterministic ippushdown automata accepting by nal state or empty pushdown. ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
Flippushdown automata are pushdown automata with the additional ability to ip or reverse its pushdown. We investigate deterministic and nondeterministic ippushdown automata accepting by nal state or empty pushdown.
Micromacro stack systems: A new frontier of decidability for sequential systems
 In 18th LICS, 381390
, 2003
"... We define the class of micromacro stack graphs, a new class of graphs modeling infinitestate sequential systems with a decidable modelchecking problem. Micromacro stack graphs are the configuration graphs of stack automata whose states are partitioned into micro and macro states. Nodes of the gr ..."
Abstract

Cited by 2 (2 self)
 Add to MetaCart
We define the class of micromacro stack graphs, a new class of graphs modeling infinitestate sequential systems with a decidable modelchecking problem. Micromacro stack graphs are the configuration graphs of stack automata whose states are partitioned into micro and macro states. Nodes of the graph are configurations of the stack automaton where the state is a macro state. Edges of the graph correspond to the sequence of micro steps that the automaton makes between macro states. We prove that this class strictly contains the class of prefixrecognizable graphs. We give a direct automatatheoretic algorithm for model checking ¢calculus formulas over micromacro stack graphs. 1
On Tally Languages and Generalized Interacting Automata
 THOMAS (EDS.), DEVELOPMENTS IN LANGUAGE THEORY IV. FOUNDATIONS, APPLICATIONS, AND PERSPECTIVES, WORLD SCIENTI PUBLISHING
, 2000
"... Devices of interconnected parallel acting sequential automata are investigated from a language theoretic point of view. Starting with the wellknown result that each tally language acceptable by a classical oneway cellular automaton (OCA) in realtime has to be a regular language we will answer th ..."
Abstract

Cited by 2 (2 self)
 Add to MetaCart
Devices of interconnected parallel acting sequential automata are investigated from a language theoretic point of view. Starting with the wellknown result that each tally language acceptable by a classical oneway cellular automaton (OCA) in realtime has to be a regular language we will answer the three natural questions `How much time do we have to provide?' `How much power do we have to plug in the single cells (i.e., how complex has a single cell to be)?' and `How can we modify the mode of operation (i.e., how much nondeterminism do we have to add)?' in order to accept nonregular tally languages. We show the surprising result that for some classes of generalized interacting automata parallelism does not lead to more accepting power than obtained by a single sequential cell. Adding a wee bit of nondeterminism an infinite hierarchy of unary language families can be shown by allowing more and more nondeterminism.
On Interacting Automata with Limited Nondeterminism
 FUND. INFORM
, 1998
"... Oneway and twoway cellular language acceptors with restricted nondeterminism are investigated. The number of nondeterministic state transitions is regarded as limited resource which depends on the length of the input. We center our attention to realtime, lineartime and unrestrictedtime computa ..."
Abstract

Cited by 2 (2 self)
 Add to MetaCart
Oneway and twoway cellular language acceptors with restricted nondeterminism are investigated. The number of nondeterministic state transitions is regarded as limited resource which depends on the length of the input. We center our attention to realtime, lineartime and unrestrictedtime computations. A speedup result that allows any lineartime computation to be spedup to realtime is proved. The relationships to deterministic arrays are considered. For an important subclass a characterization in terms of deterministic language families and fflfree homomorphisms is given. Finally we prove strong closure properties of languages acceptable with a constant number of nondeterministic transitions.