Statistical Morphological Disambiguation for Agglutinative Languages

We present statistical models for morphological disambiguation in agglutinative languages, with a specific application to Turkish. Turkish presents an interesting problem for statistical models as the potential tag set size is very large because of the productive derivational morphology. We propose to handle this by breaking up the morhosyntactic tags into inflectional groups, each of which contains the inflectional features for each (intermediate) derived form. Our statistical models score the probability of each morhosyntactic tag by considering statistics over the individual inflectional groups and surface roots in trigram models. Among the four models that we have developed and tested, the simplest model ignoring the local morphotactics within words performs the best. Our best trigram model performs with 93.95% accuracy on our test data getting all the morhosyntactic and semantic features correct. If we are just interested in syntactically relevant features and ignore a very small set of semantic features, then the accuracy increases to 95.07%.     

Some non finitely generated monoids of repetition-free endomorphisms

We answer a question raised by Mitrana in Information Processing Letters 64 about primitive morphisms, that is, morphisms that preserve primitiveness of words. Given an alphabet A with Card(A)?2, the monoid of primitive endomorphisms on A and the monoid of primitive uniform endomorphisms on A are not finitely generated. Moreover we show that it is also the case for the following monoids: the monoid of overlap-free (uniform) endomorphisms on A (when Card(A)?3), the monoid of k-power-free (uniform) endomorphisms on A (when Card(A)?2 and k?3).     

Fuzzy -ary polygroups related to fuzzy points

Recently, fuzzy n-ary sub-polygroups were introduced and studied by Davvaz, Corsini and Leoreanu-Fotea [B. Davvaz, P. Corsini, V. Leoreanu-Fotea, Fuzzy n-ary sub-polygroups, Comput. Math. Appl. 57 (2008) 141–152]. Now, in this paper, the concept of (,q)-fuzzy n-ary sub-polygroups, -fuzzy n-ary sub-polygroups and fuzzy n-ary sub-polygroup with thresholds of an n-ary polygroup are introduced and some characterizations are described. Also, we give the definition of implication-based fuzzy n-ary sub-polygroups in an n-ary polygroup, in particular, the implication operators in Łukasiewicz system of continuous-valued logic are discussed.     

密集区域无线网通信传输的研究

随着我国通信技术的不断发展和完善,无线网络的应用给我们日常生活带来了很多的便利。但对于处在不同环境下的无线网络情况,展现出各异的通信难点。该文通过分析密集区域无线Wi-Fi传输所存在的一些问题,提出几点建设性的方案。     

Bessel function of the first kind with complex argument

A new method of computing integral order Bessel functions of the first kind J_n(z) when either the absolute value of the real part or the imaginary part of the argument z = x + iy is small, is described. This method is based on computing the Bessel functions from asymptotic expressions when x∼ 0 (or y ∼ 0). These expansions are derived from the integral definition of Bessel functions. This method is necessary because some existing algorithms and methods fail to give correct results for small x small y. In addition, our overall method of computing Bessel functions of any order and argument is discussed and the logarithmic derivative is used in computing these functions. The starting point of the backward recurrence relations needed to evaluate the Bessel function and their logarithmic derivatives are investigated in order to obtain accurate numerical results. Our numerical method, together with established techniques of computing the Bessel functions, is easy to implement, efficient, and produces reliable results for all z.     

Expressive Power of Specification Languages

By abstracting away from a particular specification language and considering a ‘specification’ to be just a set of implementations, one can define a partial order on specification languages that reflects their expressive power. In addition, one can show that there is no universal specification language that can express all such ‘specifications’. Received August 1996 / Accepted in revised form April 1998     

Stochastic Inference of Regular Tree Languages

We generalize a former algorithm for regular language identification from stochastic samples to the case of tree languages. It can also be used to identify context-free languages when structural information about the strings is available. The procedure identifies equivalent subtrees in the sample and outputs the hypothesis in linear time with the number of examples. The results are evaluated with a method that computes efficiently the relative entropy between the target grammar and the inferred one.     

The dynamics of collective action

We elucidate the dynamics of ongoing collective action among intentional agents with diverse beliefs and imperfect information. The decisions on whether or not to contribute to the collective good depend not only on the past but also on their expectations as to how their actions will affect those of others. We show that in attempts at collective action the onset of overall cooperation can take place in a sudden and unexpected way. Likewise, defection can appear out of nowhere in very large, previously cooperating groups. These outbreaks mark the end of long transient states in which defection or cooperation persists in groups that cannot sustain it indefinitely. Computer experiments demonstrate these predictions, as well as verifying that diversity of beliefs among individuals acts as an additional source of uncertainty, instigating the outbreaks.     

Circuit Complexity of Regular Languages

We survey the current state of knowledge on the circuit complexity of regular languages and we prove that regular languages that are in AC⁰ and ACC⁰ are all computable by almost linear size circuits, extending the result of Chandra et al. (J. Comput. Syst. Sci. 30:222–234, 1985). As a consequence we obtain that in order to separate ACC⁰ from NC¹ it suffices to prove for some ε>0 an Ω(n ^1+ε ) lower bound on the size of ACC⁰ circuits computing certain NC¹-complete functions. Partially supported by grant GA ČR 201/07/P276, project No. 1M0021620808 of MŠMT ČR and Institutional Research Plan No. AV0Z10190503.     

Roughness in n-ary hypergroups

This paper is aimed at studying the rough sets within the context of the commutative n-ary hypergroups. For this approach, the presentation of a detailed study of the various types of n-ary subhypergroups is of the greatest importance. This study was initiated in [V. Leoreanu-Fotea, Several types of n-ary subhypergroups, Italian Journal of Pure and Applied Mathematics, in press]. Subsequently, we shall use the findings in this study to define the upper and lower approximation of a subset with respect to an invertible n-ary subhypergroup of a commutative n-ary hypergroup. In the final part, the concept of n-ary rough subhypergroup is introduced.     

Negotiating the Semantics of Agent Communication Languages

This article presents a formal framework and outlines a method that autonomous agents can use to negotiate the semantics of their communication language at run–time. Such an ability is needed in open multi–agent systems so that agents can ensure they understand the implications of the utterances that are being made and so that they can tailor the meaning of the primitives to best fit their prevailing circumstances. To this end, the semantic space framework provides a systematic means of classifying the primitives along multiple relevant dimensions. This classification can then be used by the agents to structure their negotiation (or semantic fixing ) process so that they converge to the mutually agreeable semantics that are necessary for coherent social interactions.     

Property Testing of Regular Tree Languages

We consider the edit distance with moves on the class of words and the class of ordered trees. We first exhibit a simple tester for the class of regular languages on words and generalize it to the class of ranked and unranked regular trees. We also show that this distance problem is -complete on ordered trees. A preliminary version of this paper appeared in Proceedings of 31st International Colloquium on Automata, Languages and Programming, volume 3142 of Lecture Notes in Computer Science, pages 932–944, Springer, 2005. Work supported by ACI Sécurité Informatique: VERA of the French Ministry of research.     

Regular Model Checking Using Inference of Regular Languages

Regular model checking is a method for verifying infinite-state systems based on coding their configurations as words over a finite alphabet, sets of configurations as finite automata, and transitions as finite transducers. We introduce a new general approach to regular model checking based on inference of regular languages. The method builds upon the observation that for infinite-state systems whose behaviour can be modelled using length-preserving transducers, there is a finite computation for obtaining all reachable configurations up to a certain length n. These configurations are a (positive) sample of the reachable configurations of the given system, whereas all other words up to length n are a negative sample. Then, methods of inference of regular languages can be used to generalize the sample to the full reachability set (or an overapproximation of it). We have implemented our method in a prototype tool which shows that our approach is competitive on a number of concrete examples. Furthermore, in contrast to all other existing regular model checking methods, termination is guaranteed in general for all systems with regular sets of reachable configurations. The method can be applied in a similar way to dealing with reachability relations instead of reachability sets too.     

Languages of Dot-Depth 3/2

We show that level 3/2 of the dot-depth hierarchy is decidable. More precisely, we identify a pattern  $\mathbb{B}We show that level 3/2 of the dot-depth hierarchy is decidable. More precisely, we identify a pattern such that the following holds: If F is a deterministic finite automaton that accepts L, then L belongs to level 3/2 of the dot-depth hierarchy if and only if F does not have as a subgraph in its transition graph. The latter condition can be tested in nondeterministic logarithmic space. A preliminary version of this paper was presented at the conference STACS 2000. C. Gla?er supported by Studienstiftung des Deutschen Volkes. H. Schmitz supported by Deutsche Forschungsgemeinschaft (DFG), grant Wa 847/4-1.     

Strongly Hamiltonian laceability of the even k-ary n-cube

The interconnection network considered in this paper is the k-ary n-cube that is an attractive variance of the well-known hypercube. Many interconnection networks can be viewed as the subclasses of the k-ary n-cubes include the cycle, the torus and the hypercube. A bipartite graph is Hamiltonian laceable if there exists a Hamiltonian path joining every two vertices which are in distinct partite sets. A bipartite graph G is strongly Hamiltonian laceable if it is Hamiltonian laceable and there exists a path of length N − 2 joining each pair of vertices in the same partite set, where N = |V(G)|. We prove that the k-ary n-cube is strongly Hamiltonian laceable for k is even and n  2.     

A geometric approach for shared secrets, a refinement

A refinement to the (k,n) threshold scheme proposed by Wu and He [1] is presented. It has been found that usable primes p need not be confined to the form p ≡ ±3 (mod 8) as suggested originally. Our constructive proof also lead to a different algorithm for implementation. This implementation dispenses with the directory file suggested in [1] which can be prohibitively large when the scheme is implemented with large p using the original proposal.     

研讨式教学在《程序设计语言》课程 教学中的应用研究

传统的课堂教学已不能满足学生的需求,我们必须转变教学观念,创新教学方法。研讨式教学法是一种以学 生为中心,能发挥学生学习主动性的教学方法,将有助于解决所面临的问题。从讨论《程序设计语言》课程面临的问题入手,介 绍了《程序设计语言》课程教学研究现状,进而探讨了研讨式教学在课程教学中的应用,着重剖析了研讨式教学在三个方面的 应用,并进行了评析和总结。     

A note on Lindenmayer systems,Szilard languages,spectra, and equivalence

We investigate the Szilard languages and the spectra of Lindenmayer systems through the generalization of Lindenmayer systems toK-iteration grammars and context-sensitiveK-iteration grammars. Various decidability and undecidability results are presented with respect to the evaluation of Szilard languages and spectra for particularK-iteration grammars. Further, two different definitions of the Szilard and spectral equivalence of twoK-iteration grammars are investigated.Work carried out under a National Research Council of Canada Grant No. A-7700.