1,035 research outputs found

    The Almost Equivalence by Asymptotic Probabilities for Regular Languages and Its Computational Complexities

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    We introduce p-equivalence by asymptotic probabilities, which is a weak almost-equivalence based on zero-one laws in finite model theory. In this paper, we consider the computational complexities of p-equivalence problems for regular languages and provide the following details. First, we give an robustness of p-equivalence and a logical characterization for p-equivalence. The characterization is useful to generate some algorithms for p-equivalence problems by coupling with standard results from descriptive complexity. Second, we give the computational complexities for the p-equivalence problems by the logical characterization. The computational complexities are the same as for the (fully) equivalence problems. Finally, we apply the proofs for p-equivalence to some generalized equivalences.Comment: In Proceedings GandALF 2016, arXiv:1609.0364

    Stumbling at Self in Keats's Endymion

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    Spatial Existential Positive Logics for Hyperedge Replacement Grammars

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    We study a (first-order) spatial logic based on graphs of conjunctive queries for expressing (hyper-)graph languages. In this logic, each primitive positive (resp. existential positive) formula plays a role of an expression of a graph (resp. a finite language of graphs) modulo graph isomorphism. First, this paper presents a sound- and complete axiomatization for the equational theory of primitive/existential positive formulas under this spatial semantics. Second, we show Kleene theorems between this logic and hyperedge replacement grammars (HRGs), namely that over graphs, the class of existential positive first-order (resp. least fixpoint, transitive closure) formulas has the same expressive power as that of non-recursive (resp. all, linear) HRGs

    On the Finite Variable-Occurrence Fragment of the Calculus of Relations with Bounded Dot-Dagger Alternation

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    Coleridge and Problems of Lexicography

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    Words-to-Letters Valuations for Language Kleene Algebras with Variable Complements

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    We investigate the equational theory of Kleene algebra terms with variable complements -- (language) complement where it applies only to variables -- w.r.t. languages. While the equational theory w.r.t. languages coincides with the language equivalence (under the standard language valuation) for Kleene algebra terms, this coincidence is broken if we extend the terms with complements. In this paper, we prove the decidability of some fragments of the equational theory: the universality problem is coNP-complete, and the inequational theory t <= s is coNP-complete when t does not contain Kleene-star. To this end, we introduce words-to-letters valuations; they are sufficient valuations for the equational theory and ease us in investigating the equational theory w.r.t. languages. Additionally, we prove that for words with variable complements, the equational theory coincides with the word equivalence.Comment: In Proceedings AFL 2023, arXiv:2309.0112

    SEEdit: SELinux Security Policy Configuration System with Higher Level Language

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    Security policy for SELinux is usually created by customizing a sample policy called refpolicy. However, describing and verifying security policy configurations is difficult because in refpolicy, there are more than 100,000 lines of configurations, thousands of elements such as permissions, macros and labels. The memory footprint of refpolicy which is around 5MB, is also a problem for resource constrained devices. We propose a security policy configuration system SEEdit which facilitates creating security policy by a higher level language called SPDL and SPDL tools. SPDL reduces the number of permissions by integrated permissions and removes label configurations. SPDL tools generate security policy configurations from access logs and tool user’s knowledge about applications. Experimental results on an embedded system and a PC system show that practical security policies are created by SEEdit, i.e., describing configurations is semiautomated, created security policies are composed of less than 500 lines of configurations, 100 configuration elements, and thememory footprint in the embedded system is less than 500KB

    SEEdit: SELinux Security Policy Configuration System with Higher Level Language

    Get PDF
    Security policy for SELinux is usually created by customizing a sample policy called refpolicy. However, describing and verifying security policy configurations is difficult because in refpolicy, there are more than 100,000 lines of configurations, thousands of elements such as permissions, macros and labels. The memory footprint of refpolicy which is around 5MB, is also a problem for resource constrained devices. We propose a security policy configuration system SEEdit which facilitates creating security policy by a higher level language called SPDL and SPDL tools. SPDL reduces the number of permissions by integrated permissions and removes label configurations. SPDL tools generate security policy configurations from access logs and tool user’s knowledge about applications. Experimental results on an embedded system and a PC system show that practical security policies are created by SEEdit, i.e., describing configurations is semiautomated, created security policies are composed of less than 500 lines of configurations, 100 configuration elements, and thememory footprint in the embedded system is less than 500KB

    A preliminary report on noble gases in the Kobe (CK) meteorite: A carbonaceous chondrite fell in Kobe City, Japan

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    We have investigated elemental and isotopic compositions of noble gases in the newly-fallen CK chondrite, Kobe. The relatively low concentrations of primordial heavy noble gases (Kr and Xe) and the relatively high ^Xe/^Xe ratio (6.51±0.02) are similar to those found in previous studies of CK chondrites. The calculated cosmic-ray exposure age based on cosmogenic ^Ne is 41Ma, and the K-Ar age is 2.1Ga. Based on calculated exposure ages and gas retention ages of Kobe and some other CK chondrites, it is likely that they have partially lost both radiogenic and cosmogenic He by solar heating during the time of exposure. Based on the ^Ar retention age, we interpret that Kobe may also have experienced thermal events, possibly related to impacts about 2 billion years age

    Redshift Dependent Lag-Luminosity Relation in 565 BASTE Gamma Ray Bursts

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    We compared redshifts zYz_Y from Yonetoku relation and zlagz_{lag} from the lag-luminosity relation for 565 BASTE GRBs and were surprised to find that the correlation is very low. Assuming that the luminosity is a function of both zYz_Y and the intrinsic spectral lag τlag\tau_{lag}, we found a new redshift dependent lag-luminosity relation as L=7.5×1050erg/s(1+z)2.53τlag−0.282L=7.5\times 10^{50}{\rm erg/s}(1+z)^{2.53}\tau_{lag}^{-0.282} with the correlation coefficient of 0.77 and the chance probability of 7.9×10−757.9\times 10^{-75}. To check the validity of this method, we examined the other luminosity indicator, Amati relation, using zYz_Y and the observed fluence and found the correlation coefficient of 0.92 and the chance probability of 5.2×10−1065.2\times 10^{-106}. Although the spectral lag is computed from two channels of BATSE, our new lag-luminosity relation suggests that a possible lag-luminosity relation in the \swift era should also depend on redshift
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