Rewriting Flash Memories by Message Passing

This paper constructs WOM codes that combine rewriting and error correction for mitigating the reliability and the endurance problems in flash memory. We consider a rewriting model that is of practical interest to flash applications where only the second write uses WOM codes. Our WOM code construction is based on binary erasure quantization with LDGM codes, where the rewriting uses message passing and has potential to share the efficient hardware implementations with LDPC codes in practice. We show that the coding scheme achieves the capacity of the rewriting model. Extensive simulations show that the rewriting performance of our scheme compares favorably with that of polar WOM code in the rate region where high rewriting success probability is desired. We further augment our coding schemes with error correction capability. By drawing a connection to the conjugate code pairs studied in the context of quantum error correction, we develop a general framework for constructing error-correction WOM codes. Under this framework, we give an explicit construction of WOM codes whose codewords are contained in BCH codes.Comment: Submitted to ISIT 201

Secure Querying of Recursive XML Views: A Standard XPath-based Technique

Most state-of-the art approaches for securing XML documents allow users to access data only through authorized views defined by annotating an XML grammar (e.g. DTD) with a collection of XPath expressions. To prevent improper disclosure of confidential information, user queries posed on these views need to be rewritten into equivalent queries on the underlying documents. This rewriting enables us to avoid the overhead of view materialization and maintenance. A major concern here is that query rewriting for recursive XML views is still an open problem. To overcome this problem, some works have been proposed to translate XPath queries into non-standard ones, called Regular XPath queries. However, query rewriting under Regular XPath can be of exponential size as it relies on automaton model. Most importantly, Regular XPath remains a theoretical achievement. Indeed, it is not commonly used in practice as translation and evaluation tools are not available. In this paper, we show that query rewriting is always possible for recursive XML views using only the expressive power of the standard XPath. We investigate the extension of the downward class of XPath, composed only by child and descendant axes, with some axes and operators and we propose a general approach to rewrite queries under recursive XML views. Unlike Regular XPath-based works, we provide a rewriting algorithm which processes the query only over the annotated DTD grammar and which can run in linear time in the size of the query. An experimental evaluation demonstrates that our algorithm is efficient and scales well.Comment: (2011

Self as social practice: rewriting the feminine in qualitative organizational research

This paper offers a reflexive discussion of the paradox of researching others and offering to represent multiple voices whilst suppressing the voice of the researcher. Martin’s (2002) injunction to repair research accounts by ‘letting the “I” back in’ is problematised by identifying four typically unacknowledged discursive subject positions which constitute the multiple nature of the “I” in such texts: the empirical ‘eye”, the analytical I, the authorial I and the I as semiotic shifter. It is argued that this shifting multiplicity is stabilised by the relationship between self and research text being corporeally grounded and gendered. From this discussion, three possible approaches to gender are considered: the discursive/textual approach (as developed inter alia by Foucault); the performance/social practice approach (as developed inter alia by Judith Butler) and the corporeal multiplicity approach (as developed inter alia by Elizabeth Grosz and Dorothea Olkowski). The paper concludes by suggesting a tripartite approach to writing self-multiplicity in research which extends the possibilities opened up by the social practice approach: re-citing (redeploying discursive resources in intertextuality); re-siting (changing the positioning of the self in power relations by reinscribing); and re-sighting (opening up new, virtual visions of possibility)

Frankétienne: towards an aesthetic of rewriting

This thesis examines the Haitian writer Franketienne's practice of rewriting his own texts, a feature of his work which frequently has been overlooked. It argues that rewriting shapes his oeuvre, providing him with the opportunity to mirror the characteristic openness and mobility of his principal literary aesthetic, the Spiral. Rewriting also enables him to bring out certain themes more clearly, such as zombification, deciphering, and cannibalism. These aesthetic and thematic aspects are, the thesis concludes, the most important functions at work in Franketienne's rewriting. By focusing on this practice, I am also able to chart important evolutions across the forty years of Franketienne's literary production.Addressing this issue of rewriting, I compare a corpus of Franketienne's texts with their rewritten versions, ranging from his earliest rewriting, Les Affres d'un defi (1979), through Mur a crever (1995), Ultravocal (1995), up to Les Metamorphoses de I'oiseau schizophone (1996-7) and Dezafi (2002). The first chapter outlines the main hyperbolizing tendencies in Franketienne's rewriting of his Creole text Dezafi (1975) in Les Affres d'un defi (1979) and Dezafi (2002), arguing that Les Affres d'un defi can be seen as Franketienne's first rewriting, and not just as a French translation of Dezafi. In chapter two, I demonstrate that Franketienne renews his first literary texts Mur a crever (1968) and Ultravocal (1972) after a period of some thirty years by updating their initial presentation of Spiralism to reflect later developments in his aesthetic ideas, and through the addition of new and stronger allusions to recent events in Haiti. Based on Franketienne's most major rewriting to date — Les Metamorphoses de I 'oiseau schizophone (1996-7) — chapters three and four show how Franketienne's thematic and aesthetic concerns become far more pronounced as his practice of rewriting evolves.When Franketienne rewrites, I have found that he does so mainly by accretion, integrating additions of various lengths throughout his texts, which are swelled considerably as a result. My study shows that aesthetic concerns become more pronounced through added references to the open and mobile Spiral form, and to the aesthetic processes which constitute the rewriting itself. Four such processes are detected: hyperbolization, deciphering/clarification, recapitulation, and cannibalization. In thematic terms, his rewriting develops certain key themes with greater complexity. Clearer political references are often added, in particular to the dictatorship of Francis Duvalier, as well as to recent politically significant events in Haiti, which thus bring older works up to date. Of all these processes and themes, I argue that cannibalism is the most important because of the opportunity it affords for comment on key political themes, and for summing up the rewriting process itself. Throughout Les Metamorphoses de I'oiseau schizophone cannibalism is used as a metaphor to represent both the iniquity of those in power in Haiti since 1804, and Franketienne's practice of rewriting, which is depicted as a very physical process of eating his own texts, and bringing them back up again replete with new additions

Self as social practice: rewriting the feminine in qualitative organizational research

This paper offers a reflexive discussion of the paradox of researching others and offering to represent multiple voices whilst suppressing the voice of the researcher. Martin’s (2002) injunction to repair research accounts by ‘letting the “I” back in’ is problematised by identifying four typically unacknowledged discursive subject positions which constitute the multiple nature of the “I” in such texts: the empirical ‘eye”, the analytical I, the authorial I and the I as semiotic shifter. It is argued that this shifting multiplicity is stabilised by the relationship between self and research text being corporeally grounded and gendered. From this discussion, three possible approaches to gender are considered: the discursive/textual approach (as developed inter alia by Foucault); the performance/social practice approach (as developed inter alia by Judith Butler) and the corporeal multiplicity approach (as developed inter alia by Elizabeth Grosz and Dorothea Olkowski). The paper concludes by suggesting a tripartite approach to writing self-multiplicity in research which extends the possibilities opened up by the social practice approach: re-citing (redeploying discursive resources in intertextuality); re-siting (changing the positioning of the self in power relations by reinscribing); and re-sighting (opening up new, virtual visions of possibility).self; gender; qualitative research; social practice

Ackermann Encoding, Bisimulations, and OBDDs

We propose an alternative way to represent graphs via OBDDs based on the observation that a partition of the graph nodes allows sharing among the employed OBDDs. In the second part of the paper we present a method to compute at the same time the quotient w.r.t. the maximum bisimulation and the OBDD representation of a given graph. The proposed computation is based on an OBDD-rewriting of the notion of Ackermann encoding of hereditarily finite sets into natural numbers.Comment: To appear on 'Theory and Practice of Logic Programming