A flat of a matroid is cyclic if it is a union of circuits; such flats form a lattice under inclusion and, up to isomorphism, all lattices can be obtained this way. A lattice is a Tr-lattice if all matroids whose lattices of cyclic flats are isomorphic to it are transversal. We investigate some sufficient conditions for a lattice to be a Tr-lattice; a corollary is that distributive lattices of ...

For n + 1 disjoint flats of dimension k in H, we produce a Delaunay cell which is a generalization of the Delaunay simplex associated to n + 1 points in H. Combinatorially, these Delaunay cells resemble truncated n-dimensional simplices. For certain classes of arrangements of flats in H, we prove that these Delaunay cells can be glued together to form a Delaunay complex, with the result that al...

We show how the Tutte polynomial of a matroid M can be computed from its condensed configuration, which is a statistic of its lattice of cyclic flats. The results imply that the Tutte polynomial of M is already determined by the abstract lattice of its cyclic flats together with their cardinalities and ranks. They furthermore generalize similiar statements for perfect matroid designs and near d...

We construct examples of 4-dimensional manifolds M supporting a locally CAT(0)metric, whose universal covers Q M satisfy Hruska’s isolated flats condition, and contain 2-dimensional flats F with the property that @1F Š S ,! S Š @1 Q M are nontrivial knots. As a consequence, we obtain that the group 1.M/ cannot be isomorphic to the fundamental group of any compact Riemannian manifold of nonposit...

Abstract Earthquake is one of the horrible natural disasters. With considerable developments in constructional science, experts have been able to find out factor forces that cause earthquakes damage and destructions different types buildings, including residential commercial caused by earthquake are high importance need be considered. The multi-story buildings usually weak points building, whic...

We prove that the Cayley graph of a group which is semihyperbolic but not hyperbolic contains a subset quasi-isometric to R2.

Following recovery of ACS with Side 2 electronics the temperature setpoint was lowered from a nominal value of-77 C to-81 C for the WFC in order to minimize impacts of the continuously growing hot pixel contamination. The CCDs are expected to have changes of 1-3% in overall sensitivity, with some spatial dependence (Sirianni et al. 2006) – the latter is calibrated via changes to the L-flats. We...

We study new posetsQ obtained by removing from a geometric latticeL of a biased graph certain flats indexed by a simplicial complex C. (One example of L is the lattice of flats of the vector matroid of a root system Bn.) We study the structure and compute the characteristic polynomial ofQ. With certain choices of L and C, including ones for which Q is a lattice interpolating between those of Bn...

the coastal region of chabahar gulf with 1113.7km2 area has been located in the southeast of iran. in this research, satellite images of etm+ (2004) were used in order to zoning of sedimentary environments in this gulf. methodology of this research was baesd on synthesis of supervised and unsupervised classifications in gis and envi softwares. based on studies and calculation of oif index, the ...