27625864
Path Balance Heuristic for Self-Adjusting Binary Search Trees
In (A. Subramanian, An Explanation of Splaying, Proceedings of the 14th Foundations of Software Technology and Theoretical Computer Science, LNCS Springer Verlag 880 354–365), D. Sleator suggested the following heuristic for self adjusting binary search trees: Every time an access is made, restructure the entire path from the root of the search tree to the accessed node into a balanced binary search tree on those nodes, and place all other subtrees rooted at the children of the nodes in the access path in their proper positions. We show that the method has an O(log n log log n/ log log log n) amortized complexity.
8028128
Maximal Sets of Integers with Distinct Divisors
A set of positive integers is said to have the distinct divisor property if there is an injective map that sends every integer in the set to one of its proper divisors. In 1983, P. Erdős and C. Pomerance showed that for every $c>1$, a largest subset of $[N,cN]$ with the distinct divisor property has cardinality $\sim \delta(c)N$, for some constant $\delta(c)>0$. They conjectured that $\delta(c)\sim c/2$ as $c \to \infty$. We prove their conjecture. In fact we show that there exist positive absolute constants $D_1,D_2$ such that $D_1\le c^{\beta}(c/2-\delta(c))\le D_2$ where $\beta = \log 2/\log (3/2)$.
9665741
Soft-output detection of CPM signals in frequency flat, Rayleigh fading channels
Symbol-by-symbol detection algorithms are useful in systems in which soft-decision metrics are important, e.g., systems with interleaved coded modulation. A soft-output algorithm for the detection of continuous phase modulated (CPM) signals transmitted over frequency flat, Rayleigh fading channels is developed. Since the optimum detector is computationally too complex for any practical implementation, some suboptimal detectors which give near optimal performance are proposed. Some theoretical approximations for the performance of the interleaved coded system are given. The performance of the soft-output algorithms is also extensively characterized by means of Monte-Carlo simulations.
95165110
A comparison of techniques for nondestructive composition measurements in CdZnTe substrates
We report an overview and a comparison of nondestructive optical techniques for determining alloy composition x in Cd1-xZnxTe substrates for HgCdTe epitaxy. The methods for single-point measurements include a new x-ray diffraction technique for precision lattice parameter measurements using a standard highresolution diffractometer, room-temperature photoreflectance, and low-temperature photoluminescence. We compare measurements on the same set of samples by all three techniques. Comparisons of precision and accuracy, with a discussion of the strengths and weaknesses of different techniques, are presented. In addition, a new photoluminescence excitation technique for full-wafer imaging of composition variations is described.