Total anti-symmetrische Quasigruppen

Bei der Untersuchung von Prüfziffersystemen über Quasigruppen stößt man auf die so genannten total anti-symmetrischen Quasigruppen. Bislang war ihre Existenz für alle Ordnungen $4k+2\geq 10$ ungeklärt. Ecker und Poch vermuteten 1986, dass es keine total anti-symmetrischen Quasigruppen der Ordnung $4k+2$ gibt. In der vorliegenden Arbeit widerlegen wir diese Vermutung und entwickeln Konstruktionen für total anti-symmetrische Quasigruppen der Ordnung $n$ für alle $n\neq 2,6$. Per Computersuche weisen wir außerdem nach, dass Prüfziffersysteme über einer 2-Quasigruppe der Ordnung 10, ebenso wie Prüfziffersysteme über Gruppen der Ordnung 10, nicht alle (Sprung-)Zwillingsfehler oder Sprung-Transpositionen erkennen können. Als weiteres Ergebnis zeigen wir, dass die Klasse der total anti-symmetrischen Quasigruppen keine Varietät ist

Scaling of magnetic monopoles in the pure compact QED

In the pure U(1) lattice gauge theory with the Villain action we find that the monopole mass in the Coulomb phase and the monopole condensate in the confinement phase scale according to simple power laws. This holds outside the coupling region in which on finite toroidal lattices the metastability phenomena occur. A natural explanation of the observed accuracy of the scaling behaviour would be the second order of the phase transition between both phases in the general space of couplings not far away from the Villain action.Comment: LATTICE99(Topology and Confinement) - 3 pages, 4 fig

Total anti-symmetrische Quasigruppen

Bei der Untersuchung von Prüfziffersystemen über Quasigruppen stößt man auf die so genannten total anti-symmetrischen Quasigruppen. Bislang war ihre Existenz für alle Ordnungen $4k+2\geq 10$ ungeklärt. Ecker und Poch vermuteten 1986, dass es keine total anti-symmetrischen Quasigruppen der Ordnung $4k+2$ gibt. In der vorliegenden Arbeit widerlegen wir diese Vermutung und entwickeln Konstruktionen für total anti-symmetrische Quasigruppen der Ordnung $n$ für alle $n\neq 2,6$. Per Computersuche weisen wir außerdem nach, dass Prüfziffersysteme über einer 2-Quasigruppe der Ordnung 10, ebenso wie Prüfziffersysteme über Gruppen der Ordnung 10, nicht alle (Sprung-)Zwillingsfehler oder Sprung-Transpositionen erkennen können. Als weiteres Ergebnis zeigen wir, dass die Klasse der total anti-symmetrischen Quasigruppen keine Varietät ist

Haematology in mice after weekly blood sampling for 7 weeks

No abstract availabl

Processing Succinct Matrices and Vectors

We study the complexity of algorithmic problems for matrices that are represented by multi-terminal decision diagrams (MTDD). These are a variant of ordered decision diagrams, where the terminal nodes are labeled with arbitrary elements of a semiring (instead of 0 and 1). A simple example shows that the product of two MTDD-represented matrices cannot be represented by an MTDD of polynomial size. To overcome this deficiency, we extended MTDDs to MTDD_+ by allowing componentwise symbolic addition of variables (of the same dimension) in rules. It is shown that accessing an entry, equality checking, matrix multiplication, and other basic matrix operations can be solved in polynomial time for MTDD_+-represented matrices. On the other hand, testing whether the determinant of a MTDD-represented matrix vanishes PSPACE$-complete, and the same problem is NP-complete for MTDD_+-represented diagonal matrices. Computing a specific entry in a product of MTDD-represented matrices is #P-complete.Comment: An extended abstract of this paper will appear in the Proceedings of CSR 201

Giant crystal-electric-field effect and complex magnetic behavior in single-crystalline CeRh3Si2

Single-crystalline CeRh3Si2 was investigated by means of x-ray diffraction, magnetic susceptibility, magnetization, electrical resistivity, and specific heat measurements carried out in wide temperature and magnetic field ranges. Moreover, the electronic structure of the compound was studied at room temperature by cerium core-level x-ray photoemission spectroscopy (XPS). The physical properties were analyzed in terms of crystalline electric field and compared with results of ab-initio band structure calculations performed within the density functional theory approach. The compound was found to crystallize in the orthorhombic unit cell of the ErRh3Si2 type (space group Imma -- No.74, Pearson symbol: oI24) with the lattice parameters: a = 7.1330(14) A, b = 9.7340(19) A, and c = 5.6040(11) A. Analysis of the magnetic and XPS data revealed the presence of well localized magnetic moments of trivalent cerium ions. All physical properties were found to be highly anisotropic over the whole temperature range studied, and influenced by exceptionally strong crystalline electric field with the overall splitting of the 4f1 ground multiplet exceeding 5700 K. Antiferromagnetic order of the cerium magnetic moments at TN = 4.70(1)K and their subsequent spin rearrangement at Tt = 4.48(1) K manifest themselves as distinct anomalies in the temperature characteristics of all investigated physical properties and exhibit complex evolution in an external magnetic field. A tentative magnetic B-T phase diagram, constructed for B parallel to the b-axis being the easy magnetization direction, shows very complex magnetic behavior of CeRh3Si2, similar to that recently reported for an isostructural compound CeIr3Si2. The electronic band structure calculations corroborated the antiferromagnetic ordering of the cerium magnetic moments and well reproduced the experimental XPS valence band spectrum.Comment: 32 pages, 12 figures, to appear in Physical Review

The Safe Lambda Calculus

Safety is a syntactic condition of higher-order grammars that constrains occurrences of variables in the production rules according to their type-theoretic order. In this paper, we introduce the safe lambda calculus, which is obtained by transposing (and generalizing) the safety condition to the setting of the simply-typed lambda calculus. In contrast to the original definition of safety, our calculus does not constrain types (to be homogeneous). We show that in the safe lambda calculus, there is no need to rename bound variables when performing substitution, as variable capture is guaranteed not to happen. We also propose an adequate notion of beta-reduction that preserves safety. In the same vein as Schwichtenberg's 1976 characterization of the simply-typed lambda calculus, we show that the numeric functions representable in the safe lambda calculus are exactly the multivariate polynomials; thus conditional is not definable. We also give a characterization of representable word functions. We then study the complexity of deciding beta-eta equality of two safe simply-typed terms and show that this problem is PSPACE-hard. Finally we give a game-semantic analysis of safety: We show that safe terms are denoted by `P-incrementally justified strategies'. Consequently pointers in the game semantics of safe lambda-terms are only necessary from order 4 onwards

Vortex critical behavior at the de-confinement phase transition

The de-confinement phase transition in SU(2) Yang-Mills theory is revisited in the vortex picture. Defining the world sheets of the confining vortices by maximal center projection, the percolation properties of the vortex lines in the hypercube consisting of the time axis and two spatial axis are studied. Using the percolation cumulant, the temperature for the percolation transition is seen to be in good agreement with the critical temperature of the thermal transition. The finite size scaling function for the cumulant is obtained. The critical index of the finite size scaling function is consistent with the index of the 3D Ising model.Comment: 4 pages, 4 PS figures, using revtex4, paragraph and refs added, typo correcte