Showing papers on "Chomsky hierarchy published in 1980"

A Formal Model of a Generalized CSP-like Language.

Abstract: A change dispensing machine having a change dispensing board with change receiving inlets adapted to receive change coins. The change dispensing board is reciprocated by the operation of an electric motor or an electromagnet to dispense change coins received by the change receiving inlets. Slide boards are provided under the change dispensing board, for holding the change coins received by the change receiving inlet and connecting pin holes are formed in the change dispensing board. Connecting pins engage with the connecting pin holes so that the slide boards reciprocate with the reciprocation of the change dispensing board. The connecting pins are disengaged from the connecting pin holes so that reciprocation of the slide boards is released. First elastic members provide restoring forces to said connecting pins so that solenoids are released from the reciprocation of the change dispensing board. Second elastic members provide restoring forces to the plungers so that the slide boards are reciprocated with the change dispensing board. The slide boards engage with said change dispensing board with the aid of the connecting pins when the change coins are not dispensed and are disengaged when the change coins are dispensed.

The Generative Power of Rule Orderings in Formal Grammars

Abstract: One way of 'restricting linguistic theory' is the L-view: place sufficient restrictions on the allowable rules of grammars so as to reduce their generative power. Another way is the G-view: disallow certain grammars, regardless of whether this results in a reduction of generative capacity. The present paper adopts the L-view and, consequently, investigates the generative power of various theories. One area in linguistics where restrictions on linguistic theory have been advocated is in the ordering (within the cycle) of the application of the rules which generate the language. We consider eight proposals: Total Ordering; Partial Ordering (= Total Ordering plus iterative application); Semi Ordering ( = Anderson's 'local ordering' without iterative application); Semi Partial Ordering ( = Semi Ordering plus iterative application); Unorder ings ( = Ringen 'Condition VI, unmodified'); Quasi Orderings ( = Ringen 'Condition VI, modified'); Random Orderings; and Simultaneous Application. If, for any grammar obeying rule ordering conditions A there is a grammar obeying rule ordering conditions B which contains exactly the same class of derivations, then rule ordering theory B is at least as powerful in strong generative capacity as rule ordering theory A. Similar considerations are used to define the notions of equivalent, more powerful, and noncomparable in strong generative capacity. A series of theorems are proved showing the relative strength of the eight rule ordering theories. Some linguists who advocate 'random ordering' actually have in mind random ordering plus some 'universal principles'. We investigate the effect of four of these principles from the standpoint of the L-view, showing that two of them are strongly equivalent to total orderings and that two of them are intermediate between total and partial orderings. We close with an indication of what the role of mathematical linguistics should be for the ordinary working linguist. Linguistics 18 (1980), 017-072. 0024-3949/80/0018-0017 $2.00 © Mouton Publishers, The Hague Brought to you by | University of Alberta Library

Methods for specifying families of formal languages — past-present-future

Abstract: Publisher Summary This chapter discusses the formal language theory. The methods for specifying the families of formal languages relate a number of diverse activities. The chapter discusses the different ways to describe the families of languages that are of interest to computer scientists. The formal languages arose from the study of natural languages. However, it was the work of the linguist Noam Chomsky in 1956 that is regarded as the starting point. In the paper, Chomsky presented the concept of a general phrase structure grammar. Therefore, one way to define a family of languages is by generative mechanisms, that is, by grammar. A family of languages that is not closed under intersection with regular sets should not be studied for its own right but only for other purposes. Thus, the Intersection theorem is an indication towards determining appropriate families of languages to study. Instead of concern to a scattering of linguists, logicians, and mathematicians, formal languages has become an object of study to the large group of individuals interested in the rapidly developing field of computers.

Automata, languages and programming : sixth colloquium, Graz, Austria, July 16-20, 1979

Abstract: Sharing in nondeterminism.- Sur les mots sans carre definis par un morphisme.- A characterization of abstract data as model-theoretic invariants.- Inherent ambiguities in families of grammars extended abstract.- Representing complexity classes by equality sets.- Supercounter machines.- Existential quantifiers in abstract data types.- A generalization of Ginsburg and Rose's characterization of G-S-M mappings.- Strict deterministic languages and controlled rewriting systems.- A string matching algorithm fast on the average.- Functional characterization of some semantic equalities inside ?-calculus.- Arbitration and queueing under limited shared storage requirements.- On the homomorphic characterizations of families of languages.- Two level grammars: CF-grammars with equation schemes.- Proving termination with multiset orderings.- One abstract accepting algorithm for all kinds of parsers.- Studies in abstract/concrete mappings in proving algorithm correctness.- A characterization of a dot-depth two analogue of generalized definite languages.- Partitioned LL(k) grammars.- Recursion schemes and generalized interpretations.- A rational theory of AFLs.- On the succinctness of different representations of languages.- A fixed-point theorem for recursive-enumerable languages and some considerations about fixed-point semantics of monadic programs.- Hierarchic index sequential search with optimal variable block size and its minimal expected number of comparisons.- A unique termination theorem for a theory with generalised commutative axioms.- Dags and Chomsky hierarchy.- Recent advances in the probabilistic analysis of graph-theoretic algorithms.- On the average stack size of regularly distributed binary trees.- On reductions of parallel programs.- On the height of derivation trees.- The modal logic of programs.- A comparison between two variations of a pebble game on graphs.- LL(k) parsing for attributed grammars.- On eliminating nondeterminism from Turing machines which use less than logarithm worktape space.- Structure preserving transformations on non-left-recursive grammars.- The complexity of restricted minimum spanning tree problems.- A systematic approach to formal language theory through parallel rewriting.- Extending the notion of finite index.- On the complexity of general context-free language parsing and recognition.- Space-time tradeoffs for oblivious integer multiplication.- Investigating programs in terms of partial graphs.- On the power of random access machines.- An axiomatic treatment of ALGOL 68 routines.- P-selective sets, tally languages, and the behavior of polynomial time reducibilities on NP.- Constructing call-by-value continuation semantics.- A formal semantics for concurrent systems.- On constructing LL(k) parsers.- More on advice on structuring compilers and proving them correct.- Languages of nilpotent and solvable groups (extended abstract).- Unique fixed points vs. least fixed points.- A modification of the LR(k) method for constructing compact bottom-up parsers.- Optimal decomposition of linear automata.- Bracketed two-level grammars - A decidable and practical approach to language definitions.