Rewriting Strategies Research Articles

Shoggoth: A Formal Foundation for Strategic Rewriting

Rewriting is a versatile and powerful technique used in many domains. Strategic rewriting allows programmers to control the application of rewrite rules by composing individual rewrite rules into complex rewrite strategies. These strategies are semantically complex, as they may be nondeterministic, they may raise errors that trigger backtracking, and they may not terminate. Given such semantic complexity, it is necessary to establish a formal understanding of rewrite strategies and to enable reasoning about them in order to answer questions like: How do we know that a rewrite strategy terminates? How do we know that a rewrite strategy does not fail because we compose two incompatible rewrites? How do we know that a desired property holds after applying a rewrite strategy? In this paper, we introduce Shoggoth: a formal foundation for understanding, analysing and reasoning about strategic rewriting that is capable of answering these questions. We provide a denotational semantics of System S, a core language for strategic rewriting, and prove its equivalence to our big-step operational semantics, which extends existing work by explicitly accounting for divergence. We further define a location-based weakest precondition calculus to enable formal reasoning about rewriting strategies, and we prove this calculus sound with respect to the denotational semantics. We show how this calculus can be used in practice to reason about properties of rewriting strategies, including termination, that they are well-composed, and that desired postconditions hold. The semantics and calculus are formalised in Isabelle/HOL and all proofs are mechanised.

A Learned Query Rewrite System

Query rewriting is a challenging task that transforms a SQL query to improve its performance while maintaining its result set. However, it is difficult to rewrite SQL queries, which often involve complex logical structures, and there are numerous candidate rewrite strategies for such queries, making it an NP-hard problem. Existing databases or query optimization engines adopt heuristics to rewrite queries, but these approaches may not be able to judiciously and adaptively apply the rewrite rules and may cause significant performance regression in some cases (e.g., correlated subqueries may not be eliminated). To address these limitations, we introduce LearnedRewrite, a query rewrite system that combines traditional and learned algorithms (i.e., Monte Carlo tree search + hybrid estimator) to rewrite queries. We have implemented the system in Calcite, and experimental results demonstrate LearnedRewrite achieves superior performance on three real datasets.

Dependable STT-MRAM With Emerging Approximation and Speculation Paradigms

Spin-Transfer-Torque (STT) MRAM is configured with high access speed, readily hybrid integration and guaranteed endurance/retention, which becomes one of the most promising candidates for next generation memory. However, the major challenge of STT-MRAM is its high switching energy consumption, accompanied with unreliable writing operation. This work exploits two emerging design paradigms entitled approximation and speculation MRAM. A novel design scheme with timing speculation and approximate storage is proposed to improve energy efficiency in MRAM write operation by reducing write time. Simulation results show that latency and energy loss in entire write operation can be significantly reduced. The proposed technique obtains 84%/57.4% in the symmetric and unidirectional writing operations. Meanwhile, timing speculative method improves the failure/reliability in writing by re-write strategy. Related MRAM macro specification is applied to image processing, which obtains 10% (58.8%-67.2%) of the improvement of precision in image and higher image quality is obtained under the same accuracy rate.

Three faces of recursion axioms: the case of constructive dynamic logic of relation changers

Abstract This paper proposes an intuitionistic generalization of van Benthem and Liu’s dynamic logic of relation changers, where relation changers are dynamic operators that rewrite each agent’s accessibility relation. We employ Nishimura’s Kripke semantics for a constructive propositional dynamic logic to define the semantics of relation changers. Strong completeness results of Hilbert-style axiomatizations for constructive dynamic logic of relation changers are established by two types of rewriting strategies via recursion axioms: inside-out and outside-in strategies. To establish the semantic completeness by outside-in strategy, we propose the notion of composition of relation changers and an appropriately defined notion of length of a formula. Moreover, we reveal that recursion axioms have additional two faces: semantic and proof-theoretic ones. As for the semantic face, we introduce an alternative semantics for dynamic logic of relation changers to specify the semantic meaning of recursion axioms used in the inside-out strategy. This leads us to a semantic completeness proof of the axiomatization for the original semantics, which does not require a rewriting strategy based on recursion axioms. As for the proof-theoretic face, we transform each of recursion axioms required in the outside-in strategy into two (left and right) inference rules to provide a sequent calculus for dynamic logic of relation changers. Since the resulting sequent calculus is cut-free but semi-analytic, it still enjoys the Craig interpolation theorem by Maehara’s method.

Tensor Network Rewriting Strategies for Satisfiability and Counting

We provide a graphical treatment of SAT and #SAT on equal footing. Instances of #SAT can be represented as tensor networks in a standard way. These tensor networks are interpreted by diagrams of the ZH-calculus: a system to reason about tensors over C in terms of diagrams built from simple generators, in which computation may be carried out by transformations of diagrams alone. In general, nodes of ZH diagrams take parameters over C which determine the tensor coefficients; for the standard representation of #SAT instances, the coefficients take the value 0 or 1. Then, by choosing the coefficients of a diagram to range over B, we represent the corresponding instance of SAT. Thus, by interpreting a diagram either over the boolean semiring or the complex numbers, we instantiate either the decision or counting version of the problem. We find that for classes known to be in P, such as 2SAT and #XORSAT, the existence of appropriate rewrite rules allows for efficient simplification of the diagram, producing the solution in polynomial time. In contrast, for classes known to be NP-complete, such as 3SAT, or #P-complete, such as #2SAT, the corresponding rewrite rules introduce hyperedges to the diagrams, in numbers which are not easily bounded above by a polynomial. This diagrammatic approach unifies the diagnosis of the complexity of CSPs and #CSPs and shows promise in aiding tensor network contraction-based algorithms.

Arab American Feminism: The Political and the Literary Strategies of Re-writing between Borders in Contemporary Post-9/11 Fiction by Women Writers

Undeniably, Arab American women occupy a debatable position in mainstream culture and politics. Because of their former invisibility, they started to claim their presence and to fight for their rights in post-9/11 America. They ardently become aware of their submission to both Arab patriarchy and sexism and the necessity to fight against this denigrating position. Likewise, they realise that they were silenced in discourses against Arab and Muslim discrimination in the United States. This paper focuses on the ways they have been challenging these discriminatory and invisibilizing discourses against Arab women through shedding light on their Transnational Feminist concerns in their writings, in which they have created a site to communicate anti-discrimination discourses, and to oppose the stereotypical monolithic portrayals of Arab men that are mainly due to the hypervisibility and the demonization of Arabs in post- 9/11 America. Additionally, it highlights how the Shehrazadian narrative strategy in contemporary Arab American women’s writing engulfs several features and illustrations of confrontation and resistance to the stereotypical representations of Arab women, mainly in the American popular culture. Indeed, Shehrazade and her narrative strategies become in this context a collective means for re-writing, reviving and redefining grandmother figures from the past. Shehrazed’s storytelling, as a life-serving strategy, becomes a metaphor for the urgency of exploring why and how figures like Shehrazade are translated across cultures and how Orientalism shapes such translation.

Temporal Minimal-World Query Answering over Sparse ABoxes

AbstractOntology-mediated query answering is a popular paradigm for enriching answers to user queries with background knowledge. For querying the absence of information, however, there exist only few ontology-based approaches. Moreover, these proposals conflate the closed-domain and closed-world assumption and, therefore, are not suited to deal with the anonymous objects that are common in ontological reasoning. Many real-world applications, like processing electronic health records, also contain a temporal dimension and require efficient reasoning algorithms. Moreover, since medical data are not recorded on a regular basis, reasoners must deal with sparse data with potentially large temporal gaps. Our contribution consists of two main parts: In the first part, we introduce a new closed-world semantics for answering conjunctive queries (CQs) with negation over ontologies formulated in the description logic $${\mathcal E}{\mathcal L}{{\mathcal H}_ \bot }$$ , which is based on the minimal canonical model. We propose a rewriting strategy for dealing with negated query atoms, which shows that query answering is possible in polynomial time in data complexity. In the second part, we extend this minimal-world semantics for answering metric temporal CQs with negation over the lightweight temporal logic and obtain similar rewritability and complexity results.

Achieving high-performance the functional way: a functional pearl on expressing high-performance optimizations as rewrite strategies

Optimizing programs to run efficiently on modern parallel hardware is hard but crucial for many applications. The predominantly used imperative languages - like C or OpenCL - force the programmer to intertwine the code describing functionality and optimizations. This results in a portability nightmare that is particularly problematic given the accelerating trend towards specialized hardware devices to further increase efficiency. Many emerging DSLs used in performance demanding domains such as deep learning or high-performance image processing attempt to simplify or even fully automate the optimization process. Using a high-level - often functional - language, programmers focus on describing functionality in a declarative way. In some systems such as Halide or TVM, a separate schedule specifies how the program should be optimized. Unfortunately, these schedules are not written in well-defined programming languages. Instead, they are implemented as a set of ad-hoc predefined APIs that the compiler writers have exposed. In this functional pearl, we show how to employ functional programming techniques to solve this challenge with elegance. We present two functional languages that work together - each addressing a separate concern. RISE is a functional language for expressing computations using well known functional data-parallel patterns. ELEVATE is a functional language for describing optimization strategies. A high-level RISE program is transformed into a low-level form using optimization strategies written in ELEVATE . From the rewritten low-level program high-performance parallel code is automatically generated. In contrast to existing high-performance domain-specific systems with scheduling APIs, in our approach programmers are not restricted to a set of built-in operations and optimizations but freely define their own computational patterns in RISE and optimization strategies in ELEVATE in a composable and reusable way. We show how our holistic functional approach achieves competitive performance with the state-of-the-art imperative systems Halide and TVM.

MŰFORDÍTÁS, ÚJRAÍRÁS, RECEPCIÓ

Ivo Andrić jelentős helyet foglal el a magyar irodalmi gondolkodásban. Műveiről folyamatosan jelennek meg tanulmányok, tárcák sorának címében jelenik meg utalás a Nobel-díjas regényre, a Híd a Drinánra. Poétikája a mai középnemzedék irodalmi affinitásával találkozott, s ennek során mottók és intertextuális áthallások formájában jelentkezik az andrići szövegvilág hatása. Miközben a recepció jelenségeit regisztráljuk, nem téveszthetjük szem elől, hogy Ivo Andrić munkássága nem a szerb eredeti szövegek olvasásán, hanem a fordításokon keresztül fejti ki hatását. Alkotásait pályájának kezdetétől fogva rendszeresen fordították magyar nyelvre. Dolgozatomban arra keresem a választ, hogy a fordítás jellege hogyan határozta meg a recepciót, s vajon hatott-e és hogyan irodalmi hatásának kiteljesedésére. Munkám során André Lefevere elméletéből indulok ki, aki a fordítást – a szövegmanipuláció más formáival egyetemben – újraírásként határozza meg.

Confluence of Conditional Term Rewrite Systems via Transformations

Conditional term rewriting is an intuitive yet complex extension of term rewriting. In order to benefit from the simpler framework of unconditional rewriting, transformations have been defined to eliminate the conditions of conditional term rewrite systems. Recent results provide confluence criteria for conditional term rewrite systems via transformations, yet they are restricted to CTRSs with certain syntactic properties like weak left-linearity. These syntactic properties imply that the transformations are sound for the given CTRS. This paper shows how to use transformations to prove confluence of operationally terminating, right-stable deterministic conditional term rewrite systems without the necessity of soundness restrictions. For this purpose, it is shown that certain rewrite strategies, in particular almost U-eagerness and innermost rewriting, always imply soundness.

Games for Active XML Revisited

The article studies the rewriting mechanisms for intensional documents in the Active XML framework, abstracted in the form of active context-free games. The safe rewriting problem studied in this article is to decide whether the first player, JULIET, has a winning strategy for a given game and (nested) word; this corresponds to a successful rewriting strategy for a given intensional document. The article examines several extensions of active context-free games. The primary extension allows for more expressive schemas (namely XML schemas and regular nested word languages) for both target and replacement languages and has the effect that games are played on nested words instead of (flat) words as in previous studies. Other extensions consider validation of input parameters of web services, and an alternative semantics based on insertion of values returned by the services. In general, the complexity of the safe rewriting problem is highly intractable (doubly exponential time), but the article identifies relevant tractable cases.

All about the with statement in JavaScript

The with statement in JavaScript makes static analysis of JavaScript applications difficult by introducing a new scope at run time and thus invalidating lexical scoping. Therefore, many static approaches to JavaScript program analysis and the strict mode of ECMAScript 5 simply disallow the with statement. To justify exclusion of the with statement, we should better understand the actual usage patterns of the with statement. In this paper, we present the usage patterns of the with statement in real-world JavaScript applications currently used in the 898 most popular web sites. We investigate whether we can rewrite the with statements in each pattern to other statements not using the with statement. We show that we can rewrite all the static occurrences of the with statement that do not have any dynamic code generating functions. Even though the rewriting process is not applicable to any dynamically generated with statements, our results are still promising. Because all the static approaches that disallow the with statement also disallow dynamic code generation, such static approaches can allow the with statement using our rewriting process. We formally present our rewriting strategy, provide its implementation, and show its faithfulness using extensive testing. We believe that removing with statements will simplify JavaScript program analysis designs without considering dynamic scope introduction while imposing fewer syntactic restrictions.

Improving the Students’ Achievement in Writing Descriptive Text through Prepare, Organize, Write, Edit, Rewrite (POWER) Strategy

This research concerned on Improving the Students’ Achievement in Writing Descriptive Texts through Prepare, Organize, Write, Edit, Rewrite (POWER) Strategy. In this research, the writer conducted classroom action research. Subject of this research were the second year students of SMK Negeri 1 Tanjung Pura Class XI AK consisted of 35 students. This research was conducted in two cycles. Each cycle was organized in four steps, namely Planning, Acting, Observing, and Reflecting. Cycle II was the improvement of Cycle I. There are two kinds of data collected during the research, qualitative and quantitative data. The instruments for the quantitative data was writing test while the qualitative data was gathered through Observation Sheet, Interview Sheet and Diary Notes. Findings showed that students’ score improved from Orientation Test to Test II. Based on the data analysis, Students’ mean in Orientation Test was 38.37, in Test I was 66.49, and Test II was 83.11. The conclusion is that the Prepare, Organize, Write, Edit, Rewrite (POWER) Strategy can improve the students’ achievement in writing descriptive text.

Research on Web Query Translation based on Ontology

This paper presents a framework of query translation based on ontology between different query interfaces (forms) , which will translate the queries into suitable formats, hiding the differences from underlying sources, and enabling users to access data sources conveniently. Firstly, constructing domain ontology concept model (DOCM), then, finding out predicate matching relationships between source form and target forms based on DOCM, lastly, analyzing query rewrite strategy which contains four type rewriters to construct automatically a set of constraint mapping rules so that the system can use the user-provided input values to fill out the appropriate form fields of different web database forms. Experiment results show that this method is feasible and effective.

”If you thought this story sour, sweeten it with your own telling” – Cross-cultural intertextuality and a feminist poetics of rewriting in Susan Price’s Ghost dance

The attempts to challenge conventional gendered discourses in children’s fantasy have often resulted in feminist rewritings of earlier stories. Ghost dance (1994) by the English author Susan Price is a novel that refl ects a specifi c feminist poetics of rewriting: metafi ctional passages highlight the constructedness of the narrative and at the end readers are invited to tell their own versions of the story. Moreover, the rewriting freely combines and recontextualises elements from different source texts and reformulates them to create a narrative that challenges conventional discourses of gender. While this poetics has an appeal from a feminist perspective, the play with cross-cultural intertexts and gender becomes more complex when the novel is examined in a postcolonialist framework in relation to ethnicity and the issue of cultural appropriation. Ghost dance is situated in a setting that has a real-world equivalent (Russia), involves characters that are identifi ed with names of realworld ethnic groups (Lapps (Sámi), Russian), and mixes elements from Russian wonder tales, Nordic mythology and an Ojibwe legend. The novel does not aim at historical accuracy in its representations nor is it a direct retelling of any of the pre-texts but combines motifs, themes, names, characters and settings freely from each source. In this textual melting pot, the protagonist Shingebiss is, on one level, a revision of the witch Baba Yaga, but also described as a Lappish shaman with an Ojibwe name. To rewrite gendered discourses, certain elements from the pretexts are chosen and others left out – the question is, then, what effects does this recontextualisation have on the representation of ethnicity? Or, are the feminist rewriting strategies actually a form of cultural appropriation?Keywords: children’s fantasy; gender; ethnicity; cross-cultural intertextuality; Susan Price

Strategy-Based Proof Calculus for Membrane Systems

In a previous work, we showed how rewrite strategies can be used for defining the semantics of membrane systems, in particular for expressing the different control mechanisms in membranes. The insufficient expressivity of the existing concept of rewrite strategies for describing certain control mechanisms for membranes lead us to defining a more generic concept of strategies. In this paper we introduce strategy-based rewriting logic which uses strategy controllers to reason at the higher level of computation given by the evolution of the membrane systems. We give a detailed presentation of the proof calculus, model theory, and completeness. A main consequence of the approach is that we get an algebraic semantics for membrane systems. Implementation issues are also discussed.

Stratego/XT 0.17. A language and toolset for program transformation

Stratego/XT is a language and toolset for program transformation. The Stratego language provides rewrite rules for expressing basic transformations, programmable rewriting strategies for controlling the application of rules, concrete syntax for expressing the patterns of rules in the syntax of the object language, and dynamic rewrite rules for expressing context-sensitive transformations, thus supporting the development of transformation components at a high level of abstraction. The XT toolset offers a collection of flexible, reusable transformation components, and tools for generating such components from declarative specifications. Complete program transformation systems are composed from these components. This paper gives an overview of Stratego/XT 0.17, including a description of the Stratego language and XT transformation tools; a discussion of the implementation techniques and software engineering process; and a description of applications built with Stratego/XT.

On Term-Graph Rewrite Strategies

We tackle the problem of cyclic term-graph rewriting. We first revisit the classical algorithmic approach to term-graph rewriting by providing a definition of rewrite rules of the form lhs→rhs where the left-hand sides are term-graphs and the right-hand sides are sequences of actions. Such actions, which specify how to rewrite a term-graph in a stepwise manner, contribute to simplify substantially the definition of cyclic term-graph rewriting. Then we define a new class of term-graph rewrite systems which are confluent over the so-called admissible term-graphs. Finally, we provide an efficient rewrite strategy which contracts only needed redexes and give pointers to other results regarding optimal rewrite strategies of admissible term-graphs.

Stochastic P systems and the simulation of biochemical processes with dynamic compartments

We introduce a sequential rewriting strategy for P systems based on Gillespie’s stochastic simulation algorithm, and show that the resulting formalism of stochastic P systems makes it possible to simulate biochemical processes in dynamically changing, nested compartments. Stochastic P systems have been implemented using the spatially explicit programming language M G S . Implementation examples include models of the Lotka–Volterra auto-catalytic system, and the life cycle of the Semliki Forest virus.

Lazy Context Cloning for Non-Deterministic Graph Rewriting

We define a rewrite strategy for a class of non-confluent constructor-based term graph rewriting systems and prove its correctness. Our strategy and its extension to narrowing are intended for the implementation of non-strict non-deterministic functional logic programming languages. Our strategy is based on a graph transformation, called bubbling, that avoids the construction of large contexts of redexes with distinct replacements, an expensive and frequently wasteful operation executed by competitive complete techniques.