Groundstate magnetism of the one-band Hubbard model on frustrated square lattice where both nearest-neighbour $t_1$ and next-nearest-neighbour $t_2$ hoppings are considered at half-filling revisited within mean field approximation. Two new magnetic phases detected intermediate strength $U$ relative strong frustration $t_2/t_1$, named double-stripe plaquette antiferromagnetic states, which metal...

Outlier detection is an important research area forming part of many application domains. Specific application domains call for specific detection techniques, while the more generic ones can be applied in a large number of scenarios with good results. This survey tries to provide a structured and comprehensive overview of the research on Nearest Neighbor Based Outlier Detection listing out vari...

Completion of the proof of Theorem 1. Step 6: To show (6.5), which gives the Radon–Nikodym derivative of the restriction of the distribution of X(i) − x to a small ball about the origin Recall that Bδ(u) = {y ∈ Rd : ‖y − u‖ ≤ δ}, and that νd denotes ddimensional Lebesgue measure. For a Borel subset A of Rd, let N(A) = ∑n i=1 1{Xi∈A}. It follows from the hypothesis (A.2) that for x ∈ S n with n ...

imputation algorithms replace the missing values within any particular observation by taking copies of the corresponding known values from the most similar observation found in the dataset. However, when NN algorithms are executed against large multivariate datasets the poor performance (program execution speed) of these algorithms can present major practical problems. We argue that these probl...

LetP be a Poisson process of intensity one in a squareSn of arean. We construct a random geometric graph Gn,k by joining each point of P to its k ≡ k(n) nearest neighbours. Recently, Xue and Kumar proved that if k ≤ 0.074 log n then the probability that Gn,k is connected tends to 0 as n → ∞ while, if k ≥ 5.1774 log n, then the probability that Gn,k is connected tends to 1 as n → ∞. They conject...

Since its proposal by Anderson, resonating valence bonds (RVB) formed by a superposition of fluctuating singlet pairs have been a paradigmatic concept in understanding quantum spin liquids. Here, we show that excitations related to singlet breaking on nearest-neighbour bonds describe the high-energy part of the excitation spectrum in YbMgGaO4, the effective spin-1/2 frustrated antiferromagnet o...

Random k-nearest-neighbour (RKNN) imputation is an established algorithm for filling in missing values in data sets. Assume that data are missing in a random way, so that missingness is independent of unobserved values (MAR), and assume there is a minimum positive probability of a response vector being complete. Then RKNN, with k equal to the square root of the sample size, asymptotically produ...

March 19, 2012 Type Package Title Nearest Neighbour Contingency Table Analysis Version 0.0-3 Date 2012-03-19 Author Marcelino de la Cruz Rot and Philip M. Dixon Maintainer Marcelino de la Cruz Rot Depends splancs, spatstat Description Function to test spatial segregation and association based in contingency table analysis of nearest neighbour counts following Dixon (...

A tree arbiter designed to minimize the average delay between consecutive allocations of a contentious resource is described and evaluated. The idea is to divide the competing users into nested clusters corresponding to sub-trees of varying size, and to keep the resource within the smallest cluster currently containing requests. This design reduces the number of steps in the arbitration procedu...

It is shown that bagging, a computationally intensive method, asymptotically improves the performance of nearest neighbour classifiers provided that the resample size is less than 69% of the actual sample size, in the case of with-replacement bagging, or less than 50% of the sample size, for without-replacement bagging. However, for larger sampling fractions there is no asymptotic difference be...