1,041 research outputs found
The Almost Equivalence by Asymptotic Probabilities for Regular Languages and Its Computational Complexities
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
Spatial Existential Positive Logics for Hyperedge Replacement Grammars
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
Words-to-Letters Valuations for Language Kleene Algebras with Variable Complements
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
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
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
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
We compared redshifts from Yonetoku relation and 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
and the intrinsic spectral lag , we found a new redshift
dependent lag-luminosity relation as with the correlation coefficient of 0.77
and the chance probability of . To check the validity of
this method, we examined the other luminosity indicator, Amati relation, using
and the observed fluence and found the correlation coefficient of 0.92
and the chance probability of . 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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