We investigate the long-distance asymptotic behavior of the dimer correlations in the spin-1/2 alternating XY chain both at T = 0 and at sufficiently low-temperatures. The correlations consist of the dimer longrange order part and the exponentially decaying one. Although the dimer long-range order takes the different values depending on the choice of the spin pairs, the behavior in the decaying...

In recent works [1] (BHP), a generalized universality has been proposed, linking phenomena as dissimilar as 2D magnetism and turbulence. To test these ideas, we performed a MC study of the 2DXY-model. We found that the shape of the probability distribution function for the magnetization M is non Gaussian and independent of the system size, below the Kosterlitz-Thoules temperature. However, the ...

We present a process semantics for the purely additive fragment of linear logic in which formulas denote protocols and (equivalence classes of) proofs denote multichannel concurrent processes. The polycategorical model induced by this process semantics is shown to be equivalent to the free polycategory based on the syntax (i.e., it is full and faithfully complete). This establishes that the add...

Abstract. Definitions from the theory of point processes are recalled. Models of intensity function paramaterization and maximum likelihood estimation from data are explored. Closed-form log-likelihood expressions are given for the Hawkes process, Autoregressive Conditional Duration(ACD), and Log-ACD models. The Autoregressive Conditional Intensity model is also discussed. Data from the symbol ...

Random s = 1/2 XY chains and the theory of quasi-one-dimensional ferroelectrics with hydrogen bonds L'viv-1994

There is vast empirical evidence that for many economic variables conditional variances and covariances change over time. Given the importance of heteroscedasticity in finance and macroeconomics1 it is not surprising that estimation of the time-varying volatility has attracted substantial attention in the literature. As any time-varying parameter, volatility can be modelled both with observatio...

This paper revisits the online PCA problem. Given a stream of n vectors xt ∈ R (columns of X) the algorithm must output yt ∈ R (columns of Y ) before receiving xt+1. The goal of online PCA is to simultaneously minimize the target dimension ` and the error ‖X − (XY +)Y ‖. We describe two simple and deterministic algorithms. The first, receives a parameter ∆ and guarantees that ‖X − (XY +)Y ‖ is ...

Several properties of the products of finite maximal prefix, maximal biprefix, semaphore, synchronous, maximal infix and maximal outfix codes are discussed respectively. We show that, for two nonempty subsets X and Y of A such that the product XY being thin, if XY is a maximal biprefix code, then X and Y are maximal biprefix codes. Also, it is shown that, for two finite nonempty subsets X and Y...

We study the classical n-vector (n > 3) spin glass with anisotropic quenched random Dzyaloshinskii–Moriya (DM) interaction. A random DM interaction with m independent and separated couplings defines a generalized gauge-glass model with a O(n − 2m) ⊗m O(2) rotational symmetry and a broken global reflection invariance. It is shown that this model is in the same universality class as the random-ga...