We address the chromatic number of a class of Euclidean distance graphs having vertex set Q, the 3-dimensional rational space. It is shown that if s is any positive integer with no prime factors congruent to 2 (mod 3), and G is the graph with vertex set Q where any two vertices are adjacent if and only if they are distance √ 2s apart, then G has chromatic number 4. Along the way, we obtain a fe...

This paper represents the first step in the classification of finite primitive distance transitive graphs. In it we reduce the problem to the case where the automorphism group is either almost simple or affine. Let ^ be a simple, connected, undirected graph with vertex set Q. If oc, /? e Q, then d(a, j8) denotes the distance between a and /3 in §. Let G be some group of automorphisms of §. Then...

For an error-correcting code and a distance bound, the list decoding problem is to compute all the codewords within a given distance to a received message. The bounded distance decoding problem is to find one codeword if there is at least one codeword within the given distance, or to output the empty set if there is not. Obviously the bounded distance decoding problem is not as hard as the list...

Finding the minimum vertex distance between two dis-joint convex polygons in linear time. [6] Supowit, K. J.: The relative neighborhood graph, with an application to minimum spanning trees. A note on the all-nearest-neighbor problem for convex polygons. [10] O'Rourke, J., et al.: A new linear algorithm for intersecting convex polygons.Since P nw and Q R are two linearly separable convex polygon...

We show that for any convex object Q in the plane, the average distance between the Fermat-Weber center of Q and the points in Q is at least 4∆(Q)/25, and at most 2∆(Q)/(3 √ 3), where ∆(Q) is the diameter of Q. We use the former bound to improve the approximation ratio of a load-balancing algorithm of Aronov et al. [2].

Quantum error-correcting codes play an important role in both quantum communication and quantum computation. It has experienced a great progress since the establishment of the connections between quantum codes and classical codes (see [4]). It was shown that the construction of quantum codes can be reduced to that of classical linear error-correcting codes with certain self-orthogonality proper...

Let D be a bounded domain in C". The invariant distance in D is given by I I v I \ is l \\ '/2\ l/2 Kp(z,i)K„(w,w) It is shown that one half of the length of a piecewise C1 curve y: [a, b] -* D with respect to the Bergman metric is equal to the length of y measured by pD, which implies that the associated inner distance p*D coincides (up to the factor {) with the Bergman-distance. Also it was p...

spatial pattern of trees is an important characteristic of plant communities. generating hypotheses relating to the structure of ecological communities is the aim of spatial pattern recognition. stands spatial patterns are measured and mapped by measuring tree locations in the stand and entering each coordinates into analytical frameworks. the spatial pattern of plant populations observed at an...