627 research outputs found

    Lazy AC-Pattern Matching for Rewriting

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    We define a lazy pattern-matching mechanism modulo associativity and commutativity. The solutions of a pattern-matching problem are stored in a lazy list composed of a first substitution at the head and a non-evaluated object that encodes the remaining computations. We integrate the lazy AC-matching in a strategy language: rewriting rule and strategy application produce a lazy list of terms.Comment: In Proceedings WRS 2011, arXiv:1204.531

    On the distortion of twin building lattices

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    We show that twin building lattices are undistorted in their ambient group; equivalently, the orbit map of the lattice to the product of the associated twin buildings is a quasi-isometric embedding. As a consequence, we provide an estimate of the quasi-flat rank of these lattices, which implies that there are infinitely many quasi-isometry classes of finitely presented simple groups. In an appendix, we describe how non-distortion of lattices is related to the integrability of the structural cocycle

    Investor Perceptions of Board Performance: Evidence From Uncontested Director Elections

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    This paper provides evidence that uncontested director elections provide informative polls of investor perceptions regarding board performance. We find that higher (lower) vote approval is associated with lower (higher) stock price reactions to subsequent announcements of management turnovers. In addition, firms with low vote approval are more likely to experience CEO turnover, greater board turnover, lower CEO compensation, fewer and better-received acquisitions, and more and better-received divestitures in the future. These findings hold after controlling for other variables reflecting or determining investor perceptions, suggesting that elections not only inform as a summary statistic, but incrementally inform as well

    LiFtEr: Language to Encode Induction Heuristics for Isabelle/HOL

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    Proof assistants, such as Isabelle/HOL, offer tools to facilitate inductive theorem proving. Isabelle experts know how to use these tools effectively; however, there is a little tool support for transferring this expert knowledge to a wider user audience. To address this problem, we present our domain-specific language, LiFtEr. LiFtEr allows experienced Isabelle users to encode their induction heuristics in a style independent of any problem domain. LiFtEr's interpreter mechanically checks if a given application of induction tool matches the heuristics, thus automating the knowledge transfer loop.Comment: This is the pre-print of our paper of the same title accepted at APLAS2019 (https://doi.org/10.1007/978-3-030-34175-6_14). We updated the draft after fixing the errata found by Kenji Miyamot

    The Distributional Impact of Statewide Property Tax Relief: the Michigan Case

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    This study uses data from a random survey of 2001 Michigan households to analyze the extent to which the Michigan ctreuit-breaker has been successful in reducing the income regressivity of the property tax and in changing relative property tax burdens. Because of its relatively extensive coverage, including renters as well as homeowners and the nonaged as well as the aged, the circuit-breaker has yielded a more equal distribution of income within Michigan. Its potential to change the distribution of income depends on the particular formula utilized, but redistributional effects have thus far been lamited because program participation has been positively correlated with income. To the extent that reductions in the price ofpublic services created by the circuit-breaker are perceived by households, the biggest stimulus appears to be in high property tax/high-income countiesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68848/2/10.1177_109114218301100201.pd
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