871 research outputs found
GF(2)-expansions
No full textLet Γ be a finite geometry of rank n ≥ 2 with a selected type of elements, called 'points'. Let m be the number of 'points' of Γ. Under some mild hypotheses on Γ we can consider an affine expansion of Γ to AG(m, 2). We prove that the geometries obtained by applying this construction to matroids are simply connected. Then we exploit this result to study universal covers of certain geometries arising from hyperbolic quadrics and symplectic varieties over GF(2)
Universal covers of geometries of far away type
No full textThe geometries studied in this paper are obtained from buildings of spherical type by removing all chambers at non-maximal distance from a given element or flag. I consider a number of special cases of the above construction chosen among those which most frequently appear in the literature, proving that the resulting geometry is always simply connected but for three cases of small rank defined over GF(2) and GF(4). I also compute the universal cover in those exceptional cases
Recensione dell' articolo: ( Saffer, Zsolt; Telek, Mikl ́os - "Closed form results for BMAP/G/1 vacation model with binomial type discipline" - Publ.Math.Debrecen 76 (2010), no.3-4, 359–378.)
No full textThis paper deals with the BMAP/G/1 queue service system with server vacation. In this model a batch of customers arrives at the infinite buffer queue according to a batch Markovian arrival process (BMAP). The service times are independent and identically distributed. The server occasionally takes vacations, during which no customer is served. After finishing the vacation, the server continues to serve the queue. If the server finds the queue empty upon return from vacation then it immediately takes the next vacation. The vacation periods are independent and identically distributed. For this vacation model the authors assume that the following properties are valid.
The independence property: the arrival process, the customer service times and the length of the vacation periods are independent. The non-preemptive service property: the service is non-preemptive, hence the service of the actual customer is finished before the server goes on vacation. To complete the description of the vacation model, the authors specify the discipline determining the end of service periods. Specifically, they study the BMAP/G/1 vacation model in the following two cases that are defined in the literature: under binomial-gated discipline or under binomial-exhaustive discipline. For these two models the authors prove that a specific form-functional equation can be established for the vector probability generating function (GF) of the stationary number of customers at the start of vacations. They also give a closed-form solution of this vector GF by applying a recursive method. Leonardo Pasin
Ob flat flag-transitive c.c*-geometries
No full textWe study Aat flag-transitive c.c*-geometries. We prove that, apart from one exception related to Sym(6), all these geometries are gluings in the meaning of [6]. They are obtained by gluing two copies of an affine space over GF(2). There are several ways of gluing two copies of the n-dimensional affine space over GF(2). In one way, which deserves to be called the canonical one, we get a geometry with automorphism group G = 2(2n) . L(n)(2) and covered by the truncated Coxeter complex of type D-2n. The non-canonical ways give us geometries with smaller automorphism group (G less than or equal to 2(2n) . (2(n)-1)(n)) and which seldom (never ?) can be obtained as quotients of truncated Coxeter complexes
Role of prostaglandin E2 on defective interferon-gamma production during type B acute viral hepatitis.
No full textDominant lax embeddings of polar spaces
No full textIt is known that every lax projective embedding e : Gamma -> PG(V) of a point-line geometry Gamma admits a hull, namely a projective embedding (e) over tilde: Gamma -> PG((V) over tilde) uniquely determined up to isomorphisms by the following property: V and (V) over tilde are defined over the same skewfield, say K, there is morphism of embeddings (f) over tilde : (e) over tilde -> e and, for every embedding e' : Gamma -> PG(V') with V' defined over K, if there is a morphism g : e' - e then a morphism f : e' also exists such that (f) over tilde = gf. If e = (e) over tilde then we say that e is dominant. Clearly, hulls are dominant. Let now Gamma be a non-degenerate polar space of rank n >= 3. We shall prove the following: A lax embedding e: Gamma -> PG(V) is dominant if and only if, for every geometric hyperplane H of Gamma, e(H) spans a hyperplane of PG(V). We shall also give some applications of the above result
Prevalence of risk factors for coronary heart disease in a mountain community in northern Italy.
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Night-time blood pressure and carotid artery structure in a middle aged general population.
No full textLanguage Engineering in Grammatical Framework (GF)
No full textThis thesis describes a number of practical experiments rather than theoreticalinvestigations in the area of natural language processing. The basis forthe work presented is Grammatical Framework (GF). It is a very complexsystem, which comprises among other things a grammar formalism based ontype theory and its implementation written in Haskell. GF is intended forhigh-quality machine translation (of INTERLINGUA type) in the restrictedlanguage domains.The primary concern of this thesis is however limited to the usage of GFas a piece of software. The main results are: Implementing a syntax editor, which provides a graphical user interface(GUI) for the command-line GF core. Writing a part of code for automatic generation of gramletspure Javaprograms with limited (compared to GF) functionality that can be runon PDA (Portable Device Assistants) and as applets in a browser. Writing the Russian resource grammar that takes care of the most basicmorphological and syntactic rules and serves as a standard libraryfor building application grammars (describing restricted language domains)in Russian.These results contribute to language engineering in GF on two differentlevels: Author level (end-user) constructing sentences in natural languages. Grammarian level building a grammar description, which is laterused on the author level.The last part of the thesis deals with a non-linguistic domain. In thatexperiment we try to apply functional parsing technique to the well-knownproblem of protein secondary structure prediction (bioinformatics)
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