TL;DR: In this paper, a set of 136 plot samples from a diverse old-growth bottomland forest in Southern Illinois were compared with several ordination and classification techniques using the results of a series of experiments.
Abstract: Comparisons are made among the responses of several ordination and classification techniques using a set of 136 plot samples from a diverse old-growth bottomland forest in Southern Illinois. Of the ordination techniques evaluated (PO, PCA, GO and RA), RA provided the most interpretable ordering of species and samples. The RA plot ordination was divided into three segments which correspond to major vegetation units within the study area itself and more broadly within the Southern Floodplain Forest Region. Among the classification techniques used (MINFO, MDISP and CLUSTER), MINFO produced plot clusters and species groupings which are similar to those identified by RA. Classification techniques that assume strict linearity among species or samples, that is those using the correlation coefficient or standard distance similarity measures, are less satisfactory in terms of their ability to recover informative and interpretable patterns from the data set than those techniques using logarithmic terms. Discriminant analysis was used to interpret the plot groups using various environmental variables as predictors This approach successfully provided an environmental interpretation of the group structure as identified by RA and other classification techniques. The vegetation patterns in the old-growth woods at Horseshoe Lake appear to be influenced by a complex flooding-aeration gradient.
TL;DR: In this paper, the structure and function of PP and QQ plots were introduced, and the fitting of QQ plot and PP plot were respectively used to obtain the superiority of PP in the exponential distribution.
Abstract: Introduces the structure and function of PP (Stablized Probability Plot) and QQ (Quantile-Quantile Plot), and uses MATLAB to produce two sets of exponential distribution and normal distribution. The sample number is 20 and 45 respectively. The fitting of QQ plot and PP plot are respectively used to obtain the superiority of PP in the exponential distribution. In normal distribution, the QQ plot is more advantageous.
TL;DR: In this paper, a model was proposed in which only the direct and RKKY exchanges were taken into account, and the predictions of the presented model are adequate to the experimental data contained in this plot.
Abstract: An attempt was made to explain the physical sense of the special r o /r a vs. r t /r a plot being a phase diagram for the variety of chromium compounds, especially spinels, Krok-Kowalski et al., J. Alloys Compd. 315, 62 (2001). Here r t is the ionic radius of cations in the tetrahedral positions, r o the ionic radius of cations in the octahedral positions, r a the ionic radius of anions. Therefore, a model was proposed in which only the direct and RKKY exchanges were taken into account. The predictions of the presented model are adequate to the experimental data contained in this plot.
TL;DR: Through the equivalence with context-free grammars, general methods for the solution of AND/OR graphs are obtained, though "optimality" needs a little clarification.
Abstract: which the descendents of AND nodes are processed in a sequential machine. The alternating nature is obviously itself irrelevant since an arbitrary AND/OR graph can be made alternating by the suitable addition of nodes. Only finiteness is critical. Thus there is a correspondence between finite AND/OR graphs and context-free grammars. This equivalence is of more than intellectual interest, for it shows that computational problems of AND/OR graphs may be well known and solved within the framework of context-free grammars. The standard problem of AND/OR graphs is that of \"finding a solution\" (see [4]): that is, find a subtree of the graph involving only one edge out of the OR nodes, all edges out of the AND nodes, with leaves being nodes in the original graph with no edges leaving them. A solution of an AND/OR graph is precisely a derivation tree of some sentence in the associated context-free grammar. Finding a solution is then synonymous to finding a sentence in the associated language together with its derivation tree. This problem has been solved in language theory in the form of the \"emptiness problem\" (see for example [2]). Simon and Lee [4] state, \"Although the general methods are still at large, we have found an efficient way to obtain optimal solutions to AND/OR series-parallel graphs.\" Clearly, through the equivalence with context-free grammars, we obtain general methods for the solution of AND/OR graphs, though \"optimality\" needs a little clarification. The algorithm for the emptiness problem would (normally) deliver the string whose derivation tree has fewest levels, thus finding the solution to the AND/OR graph whose longest path from start to terminal problem is minimal: as a measure of solution cost this is appealing though not the same as the cost measures of Nilsson [3]. Elaborations on the algorithm will optimize other measures. This application of language theory to AND/OR graphs, while the most significant, is not the only one possible. The equivalence of AND/OR graphs (we must of course define equivalence carefully) is unsolvable. And so on. It is also worth remarking that language theory also gains in that the graphs usually associated with regular languages are degenerate cases of context-free AND/OR graphs, while at the informal level this communication emphasizes that syntax is a problem solving tool: in programming languages syntax between program and statement allows problem decomposition. Submittal of an algorithm for consideration for publication in Communications of the ACM …
TL;DR: The Harmonic Weighted Mass (HWM) index as discussed by the authors assigns equal weight to all distances between the respective distributions: the surface between the p-p plot and the diagonal.
Abstract: We propose a quantification of the p-p plot that assigns equal weight to all distances between the respective distributions: the surface between the p-p plot and the diagonal. This surface is labeled the Harmonic Weighted Mass (HWM) index. We introduce the diagonal-deviation (d-d) plot that allows the index to be computed exactly under all circumstances. This two-dimensional d-d plot accommodates a straightforward extension to the k-sample HWM index, with k > 2. A Monte Carlo simulation based on an example involving long-term sovereign credit ratings illustrates the power of the HWM test.