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Luigi Santocanale - One of the best experts on this subject based on the ideXlab platform.
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Embeddability into relational lattices is undecidable
The Journal of Logic and Algebraic Programming, 2018Co-Authors: Luigi SantocanaleAbstract:The natural join and the inner union operations combine relations of a database. Tropashko and Spight realized that these two operations are the meet and join operations in a class of lattices, known by now as the relational lattices. They proposed then lattice theory as an algebraic approach to the theory of databases alternative to the relational algebra. Litak et al. proposed an axiomatization of relational lattices over the Signature that extends the pure lattice Signature with a constant and argued that the quasiequational theory of relational lattices over this Extended Signature is undecidable. We prove in this paper that embeddability is undecidable for relational lattices. More precisely, it is undecidable whether a finite subdirectly-irreducible lattice can be embedded into a relational lattice. Our proof is a reduction from the coverability problem of a multimodal frame by a universal product frame and, indirectly, from the representability problem for relation algebras. As corollaries we obtain the following results: the quasiequational theory of relational lattices over the pure lattice Signature is undecidable and has no finite base; there is a quasiequation over the pure lattice Signature which holds in all the finite relational lattices but fails in an infinite relational lattice.
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Embeddability into relational lattices is undecidable ⋆
2017Co-Authors: Luigi SantocanaleAbstract:The natural join and the inner union operations combine relations of a database. Tropashko and Spight realized that these two operations are the meet and join operations in a class of lattices, known by now as the relational lattices. They proposed then lattice theory as an algebraic approach to the theory of databases alternative to the relational algebra. Litak et al. proposed an axiomatization of relational lattices over the Signature that extends the pure lattice Signature with a constant and argued that the quasiequational theory of relational lattices over this Extended Signature is undecidable. We prove in this paper that embeddability is undecidable for relational lattices. More precisely, it is undecidable whether a finite subdirectly-irreducible lattice can be embedded into a relational lattice. Our proof is a reduction from the coverability problem of a multimodal frame by a universal product frame and, indirectly, from the representability problem for relation algebras. As corollaries we obtain the following results: the quasiequational theory of relational lattices over the pure lattice Signature is undecidable and has no finite base; there is a quasiequation over the pure lattice Signature which holds in all the finite relational lattices but fails in an infinite relational lattice.
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RAMiCS - Embeddability into Relational Lattices Is Undecidable
Relational and Algebraic Methods in Computer Science, 2017Co-Authors: Luigi SantocanaleAbstract:The natural join and the inner union operations combine relations of a database. Tropashko and Spight realized that these two operations are the meet and join operations in a class of lattices, known by now as the relational lattices. They proposed then lattice theory as an algebraic approach to the theory of databases alternative to the relational algebra. Litak et al. proposed an axiomatization of relational lattices over the Signature that extends the pure lattice Signature with a constant and argued that the quasiequational theory of relational lattices over this Extended Signature is undecidable. We prove in this paper that embeddability is undecidable for relational lattices. More precisely, it is undecidable whether a finite subdirectly-irreducible lattice can be embedded into a relational lattice. Our proof is a reduction from the coverability problem of a multimodal frame by a universal product frame and, indirectly, from the representability problem for relation algebras. As corollaries we obtain the following results: the quasiequational theory of relational lattices over the pure lattice Signature is undecidable and has no finite base; there is a quasiequation over the pure lattice Signature which holds in all the finite relational lattices but fails in an infinite relational lattice.
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The quasiequational theory of relational lattices, in the pure lattice Signature (embeddability into relational lattices is undecidable)
2016Co-Authors: Luigi SantocanaleAbstract:The natural join and the inner union operations combine relations of a database. Tropashko and Spight realized that these two operations are the meet and join operations in a class of lattices, known by now as the relational lattices. They proposed then lattice theory as an algebraic approach to the theory of databases alternative to the relational algebra. Litak et al. proposed an axiomatization of relational lattices over the Signature that extends the pure lattice Signature with a constant and argued that the quasiequational theory of relational lattices over this Extended Signature is undecidable. We prove in this paper that embeddability is undecidable for relational lattices. More precisely, it is undecidable whether a finite subdirectly-irreducible lattice can be embedded into a relational lattice. Our proof is a reduction from the coverability problem of a multimodal frame by a universal product frame and, indirectly, from the representability problem for relation algebras. As corollaries we obtain the following results: the quasiequational theory of relational lattices over the pure lattice Signature is undecidable and has no finite base; there is a quasiequation over the pure lattice Signature which holds in all the finite relational lattices but fails in an infinite relational lattice.
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THE QUASIEQUATIONAL THEORY OF RELATIONAL LATTICES, IN THE PURE LATTICE Signature
2016Co-Authors: Luigi SantocanaleAbstract:The natural join and the inner union operations combine relations in a database. Tropashko and Spight realized that these two operations are the meet and join operations in a class of lattices, known by now as the relational lattices. They proposed then lattice theory as an algebraic approach, alternative to the relational algebra, to the theory of databases. Litak et al. proposed an axiomatization in the Signature extending the pure lattice Signature with the header constant. They argued then that the quasiequational theory of relational lattices is undecidable in this Extended Signature. We refine this result by showing that the quasiequational theory of relational lattices in the pure lattice Signature is undecidable as well. We obtain this result as a consequence of the following statement: it is undecidable whether a finite subdirectly-irreducible lattice can be embedded into a relational lattice. Our proof of this statement is a reduction from a similar problem for relation algebras and from the coverability problem of a frame by a universal product frame. As corollaries, we also obtain the following results: the quasiequational theory of relational lattices has no finite base; there is a quasiequation which holds in all the finite lattices but fails in an infinite relational lattice.
Tijs Van Der Storm - One of the best experts on this subject based on the ideXlab platform.
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Modular interpreters with implicit context propagation
Computer Languages Systems & Structures, 2017Co-Authors: Pablo Inostroza, Tijs Van Der StormAbstract:Abstract Modular interpreters are a crucial first step towards component-based language development: instead of writing language interpreters from scratch, they can be assembled from reusable, semantic building blocks. Unfortunately, traditional language interpreters can be hard to extend because different language constructs may require different interpreter Signatures. For instance, arithmetic interpreters produce a value without any context information, whereas binding constructs require an additional environment. In this paper, we present a practical solution to this problem based on implicit context propagation. By structuring denotational-style interpreters as Object Algebras, base interpreters can be retroactively lifted into new interpreters that have an Extended Signature. The additional parameters are implicitly propagated behind the scenes, through the evaluation of the base interpreter. Interpreter lifting enables a flexible style of modular and extensible language development. The technique works in mainstream object-oriented languages, does not sacrifice type safety or separate compilation, and can be easily automated, for instance using macros in Scala or dynamic proxies in Java. We illustrate implicit context propagation using a modular definition of Featherweight Java and its extension to support side-effects, and an extensible domain-specific language for state machines. We finally investigate the performance overhead of lifting by running the DeltaBlue benchmark program in Javascript on top of a modular implementation of LambdaJS and a dedicated micro-benchmark. The results show that lifting makes interpreters roughly twice as slow because of additional call overhead. Further research is needed to eliminate this performance penalty.
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GPCE - Modular interpreters for the masses: implicit context propagation using object algebras
Sigplan Notices, 2016Co-Authors: Pablo Inostroza, Tijs Van Der StormAbstract:Modular interpreters have the potential to achieve component-based language development: instead of writing language interpreters from scratch, they can be assembled from reusable, semantic building blocks. Unfortunately, traditional language interpreters are hard to extend because different language constructs may require different interpreter Signatures. For instance, arithmetic interpreters produce a value without any context information, whereas binding constructs require an additional environment. In this paper, we present a practical solution to this problem based on implicit context propagation. By structuring denotational-style interpreters as Object Algebras, base interpreters can be retroactively lifted into new interpreters that have an Extended Signature. The additional parameters are implicitly propagated behind the scenes, through the evaluation of the base interpreter. Interpreter lifting enables a flexible style of component-based language development. The technique works in mainstream object-oriented languages, does not sacrifice type safety or separate compilation, and can be easily automated. We illustrate implicit context propagation using a modular definition of Featherweight Java and its extension to support side-effects.
Pablo Inostroza - One of the best experts on this subject based on the ideXlab platform.
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Modular interpreters for the masses: implicit context propagation using object algebras
Proceedings of the 2015 ACM SIGPLAN International Conference on Generative Programming: Concepts and Experiences - GPCE 2015, 2020Co-Authors: Pablo Inostroza, Tijs Van Der StormAbstract:International audienceModular interpreters have the potential to achieve component-based language development: instead of writing language interpreters from scratch, they can be assembled from reusable, semantic building blocks. Unfortunately, traditional language interpreters are hard to extend because different language constructs may require different interpreter Signatures. For instance, arithmetic interpreters produce a value without any context information, whereas binding constructs require an additional environment. In this paper, we present a practical solution to this problem based on implicit context propagation. By structuring denotational-style interpreters as Object Algebras, base interpreters can be retroactively lifted into new interpreters that have an Extended Signature. The additional parameters are implicitly propagated behind the scenes, through the evaluation of the base interpreter. Interpreter lifting enables a flexible style of component-based language development. The technique works in mainstream object-oriented languages, does not sacrifice type safety or separate compilation, and can be easily automated. We illustrate implicit context propagation using a modular definition of Featherweight Java and its extension to support side-effects
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Modular interpreters with implicit context propagation
Computer Languages Systems & Structures, 2017Co-Authors: Pablo Inostroza, Tijs Van Der StormAbstract:Abstract Modular interpreters are a crucial first step towards component-based language development: instead of writing language interpreters from scratch, they can be assembled from reusable, semantic building blocks. Unfortunately, traditional language interpreters can be hard to extend because different language constructs may require different interpreter Signatures. For instance, arithmetic interpreters produce a value without any context information, whereas binding constructs require an additional environment. In this paper, we present a practical solution to this problem based on implicit context propagation. By structuring denotational-style interpreters as Object Algebras, base interpreters can be retroactively lifted into new interpreters that have an Extended Signature. The additional parameters are implicitly propagated behind the scenes, through the evaluation of the base interpreter. Interpreter lifting enables a flexible style of modular and extensible language development. The technique works in mainstream object-oriented languages, does not sacrifice type safety or separate compilation, and can be easily automated, for instance using macros in Scala or dynamic proxies in Java. We illustrate implicit context propagation using a modular definition of Featherweight Java and its extension to support side-effects, and an extensible domain-specific language for state machines. We finally investigate the performance overhead of lifting by running the DeltaBlue benchmark program in Javascript on top of a modular implementation of LambdaJS and a dedicated micro-benchmark. The results show that lifting makes interpreters roughly twice as slow because of additional call overhead. Further research is needed to eliminate this performance penalty.
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GPCE - Modular interpreters for the masses: implicit context propagation using object algebras
Sigplan Notices, 2016Co-Authors: Pablo Inostroza, Tijs Van Der StormAbstract:Modular interpreters have the potential to achieve component-based language development: instead of writing language interpreters from scratch, they can be assembled from reusable, semantic building blocks. Unfortunately, traditional language interpreters are hard to extend because different language constructs may require different interpreter Signatures. For instance, arithmetic interpreters produce a value without any context information, whereas binding constructs require an additional environment. In this paper, we present a practical solution to this problem based on implicit context propagation. By structuring denotational-style interpreters as Object Algebras, base interpreters can be retroactively lifted into new interpreters that have an Extended Signature. The additional parameters are implicitly propagated behind the scenes, through the evaluation of the base interpreter. Interpreter lifting enables a flexible style of component-based language development. The technique works in mainstream object-oriented languages, does not sacrifice type safety or separate compilation, and can be easily automated. We illustrate implicit context propagation using a modular definition of Featherweight Java and its extension to support side-effects.
Wolfgang Hohl - One of the best experts on this subject based on the ideXlab platform.
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Hardware support for error detection in multiprocessor systems — a case study
Microprocessors and Microsystems, 1993Co-Authors: Wolfgang Hohl, Edgar Michel, András PatariczaAbstract:Abstract A comparison of the most important methods for error detection in multiprocessor systems is presented based upon the experiences gained in the development of the fault-tolerant multiprocessor system MEMSY. A detailed comparison between watchdog processors and master-checker type duplication based fault tolerance is given, from the point of view of fault coverage, hardware and time overhead. It is shown that a simple multiplication in itself is insufficient to assure proper error detection features, especially if a low error latency time is required. Design guidelines are presented for the effective use of the duplication, based on the master-checker mode. Additionally a new general purpose watchdog processor architecture is proposed, which monitors the behaviour of the main processor by checking the control flow of processes using an Extended Signature integrity checking (ESIC) method. The watchdog processor is independent of the architecture of the main processor because it is linked to the main processor by a memory interface. The watchdog processor is convenient for multiprocessor systems based on standard components and a RISC/CISC processor with large cache as node processor.
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Concurrent Error Detection Using Watchdog Processors in the Multiprocessor System MEMSY
Fault-Tolerant Computing Systems, 1991Co-Authors: Edgar Michel, Wolfgang HohlAbstract:In this paper a proposal for an architecture of a general purpose watchdog processor is made. This watchdog processor monitors the behavior of the main processor by checking the control flow of processes using the Extended Signature Integrity Checking method (ESIC). The watchdog processor is independent of the architecture of the main processor because it is linked to the main processor by a memory interface.
Tijs Van Der Storm - One of the best experts on this subject based on the ideXlab platform.
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Modular interpreters for the masses: implicit context propagation using object algebras
Proceedings of the 2015 ACM SIGPLAN International Conference on Generative Programming: Concepts and Experiences - GPCE 2015, 2020Co-Authors: Pablo Inostroza, Tijs Van Der StormAbstract:International audienceModular interpreters have the potential to achieve component-based language development: instead of writing language interpreters from scratch, they can be assembled from reusable, semantic building blocks. Unfortunately, traditional language interpreters are hard to extend because different language constructs may require different interpreter Signatures. For instance, arithmetic interpreters produce a value without any context information, whereas binding constructs require an additional environment. In this paper, we present a practical solution to this problem based on implicit context propagation. By structuring denotational-style interpreters as Object Algebras, base interpreters can be retroactively lifted into new interpreters that have an Extended Signature. The additional parameters are implicitly propagated behind the scenes, through the evaluation of the base interpreter. Interpreter lifting enables a flexible style of component-based language development. The technique works in mainstream object-oriented languages, does not sacrifice type safety or separate compilation, and can be easily automated. We illustrate implicit context propagation using a modular definition of Featherweight Java and its extension to support side-effects
