... 573 It is immediately observable that if we parenthesize a t'mite state grammar which ge... more ... 573 It is immediately observable that if we parenthesize a t'mite state grammar which generates a language that is noncounting according to [15], the parenthesis language thus obtained is noncounting according to our definition, and vice versa. ...
ABSTRACT Associative Language Descriptions are a recent grammar model, theoretically less powerfu... more ABSTRACT Associative Language Descriptions are a recent grammar model, theoretically less powerful than Context Free grammars, but adequate for describing the syntax of programming languages. ALD do not use nonterminal symbols, but rely on permissible contexts for specifying valid syntax trees. In order to assess ALD adequacy, we analyze the descriptional complexity of structurally equivalent CF and ALD grammars, finding comparable measures. The compression obtained using CF copy rules is matched by context inheritance in ALD. The family of hierarchical parentheses languages, an abstract paradigm of HTML, and of expressions with operator precedences are studied in detail. A complete ALD grammar of Pascal is presented to testify of the practicality of the ALD approach. Keywords: Context Free Grammars, Associative Grammars, Grammar Size, Context Inheritance, Descriptional Complexity. 1.
ABSTRACT A generalization of context-free grammars and languages is presented. Generalized contex... more ABSTRACT A generalization of context-free grammars and languages is presented. Generalized context-free, or gcf, languages strictly include the cf ones but, unlike most past proposed extensions, remain semilinear. Gcf grammars combine the usage of the depthfirst rewriting discipline with the breadth-first one; the recognizers of gcf languages have tapes handled as pushdown (LIFO) or queue (FIFO) storages. This paper proves for gcf languages a partial analogous of the classical Chomsky-Schutzenberger theorem of the cf ones: every gcf language is the hom. image of the intersection of the generalized Dyck language with a regular language. The proof requires the computation of the adjacencies of letters in the strings of gcf languages. This problem is solved by means of algebraic methods, based on an adjacency-preserving compression of strings. 1 Introduction Many variations on the theme of formal grammars have been advanced since Chomsky 's classification of grammar types [20], but the context-fr...
This paper has the goals (1) of unifying top-down parsing with shift-reduce parsing to yield a si... more This paper has the goals (1) of unifying top-down parsing with shift-reduce parsing to yield a single simple and consistent framework, and (2) of producing provably correct parsing methods, deterministic as well as tabular ones, for extended context-free grammars (EBNF) represented as state-transition networks. Departing from the traditional way of presenting as independent algorithms the deterministic bottom-up LR(1), the top-down LL(1) and the general tabular (Earley) parsers, we unify them in a coherent minimalist framework. We present a simple general construction method for EBNF ELR(1) parsers, where the new category of convergence conflicts is added to the classical shift-reduce and reduce-reduce conflicts; we prove its correctness and show two implementations by deterministic push-down machines and by vector-stack machines, the latter to be also used for Earley parsers. Then the Beatty's theoretical characterization of LL(1) grammars is adapted to derive the extended ELL(1 parsing method, first by minimizing the ELR(1) parser and then by simplifying its state information. Through using the same notations in the ELR(1) case, the extended Earley parser is obtained. Since all the parsers operate on compatible representations, it is feasible to combine them into mixed mode algorithms.
ABSTRACT . This original method for specifying and checking the sequences of events taking place ... more ABSTRACT . This original method for specifying and checking the sequences of events taking place in process scheduling brings the classical syntax-directed approach of compilation to this new area. The formal language of scheduling events cannot be specified by BNF grammars, but we use instead the Augmented BNF grammars, which combine breadth-- first and depth-first derivations. Their recognizers feature one or more FIFO or LIFO tapes. The basic scheduling policies are covered: FCFS, time-slicing, mutex. Combined policies, such as readers/writers and background /foreground, are obtainable by composition. Constraints on the minimum number of data structures (i.e. queues) for priority scheduling policies may be proved by using a pumping lemma. The construction of schedule checkers is presented in the form of augmented LL(1) parsers. For scheduling algorithms, such as shortest job first, which depend on parameters and in particular on time, a syntax-directed approach is proposed, whi...
... fissato, i particolari valori il/2 .../~ influiseono sulla velocita dell'algoritmo, cio~... more ... fissato, i particolari valori il/2 .../~ influiseono sulla velocita dell'algoritmo, cio~ per ogni caso I, di//il tempo di ealeolo sara in generale funzione di I,, oltre che din. ... Si prefe-risce perci6 limitarsi a due easi significativi, noti come no~na del caso peggiore e norma del caso medio. ...
A methodology for designing and implementing program construction systems using relational data b... more A methodology for designing and implementing program construction systems using relational data bases is presented. Relations are the only data structures used by them and in the definition of interfaces between subsystems. A special-purpose relational database manager (RDB) has been designed for this application.Two large projects using this approach are described. ART (Ada-Relational-Translator) is an experimental compiler-interpreter for ADA in which all subsystems, including parser, semantic analyzer, interpreter and kernel, use relations as their only data structure; the relational approach has been pushed to the upmost to achieve fast prototyping. MML (Multi-Micro Line) is a tool-set for constructing program programs for multi-microprocessors targets, in which relations are used for allocation and configuration control. Both experiences confirm the validity of the approach for managing team work in evolving projects.
Proceedings of third international workshop on MapReduce and its Applications Date - MapReduce '12, 2012
ABSTRACT Research has proved that machine learning and iterative compilation techniques can be pr... more ABSTRACT Research has proved that machine learning and iterative compilation techniques can be profitable when applied to compilers to improve the optimizations they perform on programs. Unfortunately, these techniques are hampered by the long training times they require. This paper shows that parallel execution of multiple training runs can be naturally mapped on the MapReduce programming model and is effective in reducing execution times for iterative compilation. The presented technique allows parallel execution on multiple identical worker nodes or on a single machine by splitting its resources. Experimental results show that an almost-linear speedup can be obtained.
The classical logical antinomy known as Richard-Berry paradox is combined with plausible assumpti... more The classical logical antinomy known as Richard-Berry paradox is combined with plausible assumptions about the size i.e. the descriptional complexity of Turing machines formalizing certain sentences, to show that formalization of language leads to contradiction.
... 573 It is immediately observable that if we parenthesize a t'mite state grammar which ge... more ... 573 It is immediately observable that if we parenthesize a t'mite state grammar which generates a language that is noncounting according to [15], the parenthesis language thus obtained is noncounting according to our definition, and vice versa. ...
ABSTRACT Associative Language Descriptions are a recent grammar model, theoretically less powerfu... more ABSTRACT Associative Language Descriptions are a recent grammar model, theoretically less powerful than Context Free grammars, but adequate for describing the syntax of programming languages. ALD do not use nonterminal symbols, but rely on permissible contexts for specifying valid syntax trees. In order to assess ALD adequacy, we analyze the descriptional complexity of structurally equivalent CF and ALD grammars, finding comparable measures. The compression obtained using CF copy rules is matched by context inheritance in ALD. The family of hierarchical parentheses languages, an abstract paradigm of HTML, and of expressions with operator precedences are studied in detail. A complete ALD grammar of Pascal is presented to testify of the practicality of the ALD approach. Keywords: Context Free Grammars, Associative Grammars, Grammar Size, Context Inheritance, Descriptional Complexity. 1.
ABSTRACT A generalization of context-free grammars and languages is presented. Generalized contex... more ABSTRACT A generalization of context-free grammars and languages is presented. Generalized context-free, or gcf, languages strictly include the cf ones but, unlike most past proposed extensions, remain semilinear. Gcf grammars combine the usage of the depthfirst rewriting discipline with the breadth-first one; the recognizers of gcf languages have tapes handled as pushdown (LIFO) or queue (FIFO) storages. This paper proves for gcf languages a partial analogous of the classical Chomsky-Schutzenberger theorem of the cf ones: every gcf language is the hom. image of the intersection of the generalized Dyck language with a regular language. The proof requires the computation of the adjacencies of letters in the strings of gcf languages. This problem is solved by means of algebraic methods, based on an adjacency-preserving compression of strings. 1 Introduction Many variations on the theme of formal grammars have been advanced since Chomsky 's classification of grammar types [20], but the context-fr...
This paper has the goals (1) of unifying top-down parsing with shift-reduce parsing to yield a si... more This paper has the goals (1) of unifying top-down parsing with shift-reduce parsing to yield a single simple and consistent framework, and (2) of producing provably correct parsing methods, deterministic as well as tabular ones, for extended context-free grammars (EBNF) represented as state-transition networks. Departing from the traditional way of presenting as independent algorithms the deterministic bottom-up LR(1), the top-down LL(1) and the general tabular (Earley) parsers, we unify them in a coherent minimalist framework. We present a simple general construction method for EBNF ELR(1) parsers, where the new category of convergence conflicts is added to the classical shift-reduce and reduce-reduce conflicts; we prove its correctness and show two implementations by deterministic push-down machines and by vector-stack machines, the latter to be also used for Earley parsers. Then the Beatty's theoretical characterization of LL(1) grammars is adapted to derive the extended ELL(1 parsing method, first by minimizing the ELR(1) parser and then by simplifying its state information. Through using the same notations in the ELR(1) case, the extended Earley parser is obtained. Since all the parsers operate on compatible representations, it is feasible to combine them into mixed mode algorithms.
ABSTRACT . This original method for specifying and checking the sequences of events taking place ... more ABSTRACT . This original method for specifying and checking the sequences of events taking place in process scheduling brings the classical syntax-directed approach of compilation to this new area. The formal language of scheduling events cannot be specified by BNF grammars, but we use instead the Augmented BNF grammars, which combine breadth-- first and depth-first derivations. Their recognizers feature one or more FIFO or LIFO tapes. The basic scheduling policies are covered: FCFS, time-slicing, mutex. Combined policies, such as readers/writers and background /foreground, are obtainable by composition. Constraints on the minimum number of data structures (i.e. queues) for priority scheduling policies may be proved by using a pumping lemma. The construction of schedule checkers is presented in the form of augmented LL(1) parsers. For scheduling algorithms, such as shortest job first, which depend on parameters and in particular on time, a syntax-directed approach is proposed, whi...
... fissato, i particolari valori il/2 .../~ influiseono sulla velocita dell'algoritmo, cio~... more ... fissato, i particolari valori il/2 .../~ influiseono sulla velocita dell'algoritmo, cio~ per ogni caso I, di//il tempo di ealeolo sara in generale funzione di I,, oltre che din. ... Si prefe-risce perci6 limitarsi a due easi significativi, noti come no~na del caso peggiore e norma del caso medio. ...
A methodology for designing and implementing program construction systems using relational data b... more A methodology for designing and implementing program construction systems using relational data bases is presented. Relations are the only data structures used by them and in the definition of interfaces between subsystems. A special-purpose relational database manager (RDB) has been designed for this application.Two large projects using this approach are described. ART (Ada-Relational-Translator) is an experimental compiler-interpreter for ADA in which all subsystems, including parser, semantic analyzer, interpreter and kernel, use relations as their only data structure; the relational approach has been pushed to the upmost to achieve fast prototyping. MML (Multi-Micro Line) is a tool-set for constructing program programs for multi-microprocessors targets, in which relations are used for allocation and configuration control. Both experiences confirm the validity of the approach for managing team work in evolving projects.
Proceedings of third international workshop on MapReduce and its Applications Date - MapReduce '12, 2012
ABSTRACT Research has proved that machine learning and iterative compilation techniques can be pr... more ABSTRACT Research has proved that machine learning and iterative compilation techniques can be profitable when applied to compilers to improve the optimizations they perform on programs. Unfortunately, these techniques are hampered by the long training times they require. This paper shows that parallel execution of multiple training runs can be naturally mapped on the MapReduce programming model and is effective in reducing execution times for iterative compilation. The presented technique allows parallel execution on multiple identical worker nodes or on a single machine by splitting its resources. Experimental results show that an almost-linear speedup can be obtained.
The classical logical antinomy known as Richard-Berry paradox is combined with plausible assumpti... more The classical logical antinomy known as Richard-Berry paradox is combined with plausible assumptions about the size i.e. the descriptional complexity of Turing machines formalizing certain sentences, to show that formalization of language leads to contradiction.
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