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981.
982.
983.
984.
《Journal of Graph Theory》2018,89(3):304-326
A famous conjecture of Gyárfás and Sumner states for any tree T and integer k, if the chromatic number of a graph is large enough, either the graph contains a clique of size k or it contains T as an induced subgraph. We discuss some results and open problems about extensions of this conjecture to oriented graphs. We conjecture that for every oriented star S and integer k, if the chromatic number of a digraph is large enough, either the digraph contains a clique of size k or it contains S as an induced subgraph. As an evidence, we prove that for any oriented star S, every oriented graph with sufficiently large chromatic number contains either a transitive tournament of order 3 or S as an induced subdigraph. We then study for which sets of orientations of P4 (the path on four vertices) similar statements hold. We establish some positive and negative results. 相似文献
985.
Seung Jun Chang 《Integral Transforms and Special Functions》2018,29(1):1-15
The goal of this paper is to establish a more generalized Cameron–Storvick theorem with respect to the conditional generalized integral transform (CGIT) and the generalized first variation. Many results and formulas for Cameron–Storvick theorems established in previous papers are included. We first introduce a CGIT and a generalized first variation of functionals by using the concept of the Gaussian process and bounded linear operators. We then give the existence of them for the exponential functionals on function space. We next establish a generalized Cameron–Storvick theorem. Finally, we describe some applications. 相似文献
986.
Asymptotic constraint qualifications and global error bounds for convex inequalities 总被引:2,自引:0,他引:2
Received October 26, 1996 / Revised version received October 1, 1997 Published online October 9, 1998 相似文献
987.
Variable responses are fundamental for all experiments, and they can consist of information-rich, redundant, and low signal intensities. A dataset can consist of a collection of variable responses over multiple classes or groups. Usually some of the variables are removed in a dataset that contain very little information. Sometimes all the variables are used in the data analysis phase. It is common practice to discriminate between two distributions of data; however, there is no formal algorithm to arrive at a degree of separation (DS) between two distributions of data. The DS is defined herein as the average of the sum of the areas from the probability density functions (PDFs) of A and B that contain a ≥ percentage of A and/or B. Thus, DS90 is the average of the sum of the PDF areas of A and B that contain ≥90% of A and/or B. To arrive at a DS value, two synthesized PDFs or very large experimental datasets are required. Experimentally it is common practice to generate relatively small datasets. Therefore, the challenge was to find a statistical parameter that can be used on small datasets to estimate and highly correlate with the DS90 parameter. Established statistical methods include the overlap area of the two data distribution profiles, Welch’s t-test, Kolmogorov–Smirnov (K–S) test, Mann–Whitney–Wilcoxon test, and the area under the receiver operating characteristics (ROC) curve (AUC). The area between the ROC curve and diagonal (ACD) and the length of the ROC curve (LROC) are introduced. The established, ACD, and LROC methods were correlated to the DS90 when applied on many pairs of synthesized PDFs. The LROC method provided the best linear correlation with, and estimation of, the DS90. The estimated DS90 from the LROC (DS90–LROC) is applied to a database, as an example, of three Italian wines consisting of thirteen variable responses for variable ranking consideration. An important highlight of the DS90–LROC method is utilizing the LROC curve methodology to test all variables one-at-a-time with all pairs of classes in a dataset. 相似文献
988.
In this paper we address the problem of cooperation and collision avoidance for Lagrangian systems with input disturbances. We design control laws that guarantee cooperation as well as collision-free maneuvers. We show, using a two-step proof, that the avoidance part of the control laws guarantees safety of the agents independently of the coordinating part. Then, we establish an ultimate bound on the region to which all the agents converge to. The obtained theoretical results are illustrated through numerical examples. 相似文献
989.
990.
The characteristic finite difference fractional steps methods for compressible two-phase displacement problem 总被引:3,自引:0,他引:3
Yirang Yuan 《中国科学A辑(英文版)》1999,42(1):48-57
For compressible two-phase displacement problem, a kind of characteristic finite difference fractional steps schemes is put
forward and thick and thin grids are used to form a complete set. Some techniques, such as piecewise biquadratic interpolation,
of calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference
operators and prior estimates are adopted. Optimal order estimates inL
2 norm are derived to determine the error in the approximate solution.
Project supported by the National Scaling Program, the National Tackling Key Problems Program and the Doctorate Foundation
of the State Education Commission of China. 相似文献