Published online by Cambridge University Press: 25 June 2025
Selecting N random points in a unit square corresponds to selecting a random permutation. Placing symmetry restrictions on the points, we obtain special kinds of permutations: involutions, signed permutations and signed involutions. We are interested in the statistics of the length (in numbers of points) of the longest up/right path in each symmetry type as the number of points increases to infinity. The limiting distribution functions are expressed in terms of a Painleve II equation. In addition to the Tracy-Widom distributions of random matrix theory, we also obtain two new classes of distribution functions interpolating between the GOE and GSE, and between the GUE and GOE2 Tracy-Widom distribution functions. Applications to random vicious walks and site percolation are also discussed
1. Introduction
Suppose that we are selecting n points, p1 , p 2 , … , pn , at random in a rectangle, say R = [0,1] x [0,1] (see Figure 1). We denote by π the configuration of n random points. With probability 1, no two points have same x -coordinates nor -coordinates. An up/right path of π is a collection of points pi1, pi2, … ,pik such that x(pil) < x(pi2) < • • • < x(pik) and y(pi1)< y(pi2) < • • • < y (pik). The length of such a path is defined by the number of the points in the path. Now we denote by ln(π) the length of the longest up/right path of a random points configuration π.
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