A minimal partition problem with trace constraint in the Grushin plane

We study a variational problem for the perimeter associated with the Grushin plane, called minimal partition problem with trace constraint. This consists in studying how to enclose three prescribed areas in the Grushin plane, using the least amount of perimeter, under an additional “one-dimensional” constraint on the intersections of their boundaries. We prove existence of regular solutions for this problem, and we characterize them in terms of isoperimetric sets, showing differences with the Euclidean case. The problem arises from the study of quantitative isoperimetric inequalities and has connections with the theory of minimal clusters.     

A combinatorial correspondence related to Göllnitz' (big) partition theorem and applications

In recent work, Alladi, Andrews and Gordon discovered a key identity which captures several fundamental theorems in partition theory. In this paper we construct a combinatorial bijection which explains this key identity. This immediately leads to a better understanding of a deep theorem of Göllnitz, as well as Jacobi's triple product identity and Schur's partition theorem.

     

On the equality of two plane partition correspondences

The study of column-strict plane partitions and Young tableax has spawned numerous constructive correspondences. Among these are correspondences found in the work of Bender and Knuth that send one column-strict plane partition to another, causing a specified permutation on the numbers of parts of a given size. Another correspondence, created by Schützenberger to act on standard Young tableaux and defined in an entirely different manner. has intimate connections with the Robinson-Schensted algorithm. In this paper, these correspondences are generalized to skew column-strict plane partitions and certain of their basic properties are considered. In particular, it is shown that the correspondence of Schützenberger can be considered a special case of the Bender-Knuth correspondences.     

Asymptotic analysis of expectations of plane partition statistics

Assuming that a plane partition of the positive integer n is chosen uniformly at random from the set of all such partitions, we propose a general asymptotic scheme for the computation of expectations of various plane partition statistics as n becomes large. The generating functions that arise in this study are of the form Q(x)F(x), where \(Q(x)=\prod _{j=1}^\infty (1-x^j)^{-j}\) is the generating function for the number of plane partitions. We show how asymptotics of such expectations can be obtained directly from the asymptotic expansion of the function F(x) around \(x=1\). The representation of a plane partition as a solid diagram of volume n allows interpretations of these statistics in terms of its dimensions and shape. As an application of our main result, we obtain the asymptotic behavior of the expected values of the largest part, the number of columns, the number of rows (that is, the three dimensions of the solid diagram) and the trace (the number of cubes in the wall on the main diagonal of the solid diagram). Our results are similar to those of Grabner et al. (Comb Probab Comput 23:1057–1086, 2014) related to linear integer partition statistics. We base our study on the Hayman’s method for admissible power series.     

The Hillman-Grassl correspondence and the enumeration of reverse plane partitions

Hillman and Grassl have devised a correspondence between reverse plane partitions and nonnegative integer arrays of the same shape that allowed them to easily enumerate reverse plane partitions and provided a combinatorial connection between hook lengths and plane partitions. In this work, a collection of properties of this correspondence are presented, including two characterizations that relate this map to the familiar Schensted-Knuth correspondence. These properties are used to derive simple expressions for the generating functions of reverse plane partitions and symmetric reverse plane partitions with respect to sums along the diagonals. Equally general results are obtained for shifted reverse plane partitions using a new type of hook, thereby proving a conjecture of Stanley.     

The conjugate trace and trace of a plane partition

The conjugate trace and trace of a plane partition are defined, and the generating function for the number of plane partitions π of n with ?r rows and largest part ?m, with conjugate trace t (or trace t, when m = ∞), is found. Various properties of this generating function are studied. One consequence of these properties is a formula which can be regarded as a q-analog of a well-known result arising in the representation theory of the symmetric group.     

Enumeration of coloured plane trees with a given type partition

Tutte's result for the number of planted plane trees with a given degree partition is rederived by a variety of methods and in particular by a simple piecewise construction technique. A theorem of Gordon and Temple is applied in order to give a general relationship between the number of planted plane trees and the number of rooted plane trees and the degree partition restriction is generalised to type partition. The piecewise construction method is successfully used to derive the number of planted plane trees with a given 2-colour degree partition, also derived by Tutte, and an algorithm for the k-coloured case is developed. This algorithm may be used to obtain more specific results. These models are relevant to the statistical mechanics of polymers and this is discussed briefly.     

The Potts model representation and a Robinson–Schensted correspondence for the partition algebra

We construct a correspondence between the set of partitions of a finite set M and the set of pairs of walks to the same vertex on a graph giving the Bratteli diagram of the partition algebra on M. This is the precise analogue of the correspondence between the set of permutations of a finite set and the set of pairs of Young tableaux of the same shape, called the Robinson–Schensted correspondence.     

The limiting distribution of the trace of a random plane partition

We study the asymptotic behaviour of the trace (the sum of the diagonal parts) τ _n = τ _n (ω) of a plane partition ω of the positive integer n, assuming that ω is chosen uniformly at random from the set of all such partitions. We prove that (τ _n − c ₀ n ^2/3)/c ₁ n ^1/3 log^1/2 n converges weakly, as n → ∞, to the standard normal distribution, where c ₀ = ζ(2)/ [2ζ(3)]^2/3, c ₁ = √(1/3/) [2ζ(3)]^1/3 and ζ(s) = Σ _j=1^∞ j ^−s . Partial support given by the National Science Fund of the Bulgarian Ministry of Education and Science, grant No. VU-MI-105/2005.     

A partition identity

Let n₁+n₂+?+n_m=n where the n_i's are integers (possibly negative or greater than n). Let p=(k₁,…,k_m), where k₁+k₂+?+k_m=k, be a partition of the nonnegative integer k into m nonnegative integers and let P denote the set of all such partitions. For m?2, we prove the combinatorial identity

$\text{∑}\text{p∈P}\text{∏}\text{i=1}\text{m}\text{n}{}_{\mathrm{i}}\text{+1?k}{}_{\mathrm{i}}\text{k}{}_{\mathrm{i}}\text{=}\text{∑}\text{i?0}\text{j+m?2}\text{m?2}\text{n+1?k?2}{}_{\mathrm{j}}\text{k?2}{}_{\mathrm{j}}$

which implies the surprising result that the left side of the above equation depends on n but not on the n_i's.     

A graph partition problem

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A four-parameter partition identity

We present a new partition identity and give a combinatorial proof of our result. This generalizes a result of Andrews in which he considers the generating function for partitions with respect to size, number of odd parts, and number of odd parts of the conjugate. 2000 Mathematics Subject Classification Primary—05A17; Secondary—11P81     

A chromatic partition polynomial

A polynomial in two variables is defined by C_n(x,t)=Σ_πΠnx(Gπ,x)t^|π|, where Π_n is the lattice of partitions of the set {1, 2, …, n}, G_π is a certain interval graph defined in terms of the partition gp, χ(G_π, x) is the chromatic polynomial of G_π and |π| is the number of blocks in π. It is shown that , where S(n, i) is the Stirling number of the second kind and (x)_i = x(x − 1) ··· (x − i + 1). As a special case, C_n(−1, −t) = A_n(t), where A_n(t) is the nth Eulerian polynomial. Moreover, A_n(t)=Σ_πΠna_πt^|π| where a_π is the number of acyclic orientations of G_π.     

A matrix partition problem

In the set of positive definite semi-integral symmetric matrices we propose a partition problem. Then by introducing the notion of “additively prime” we obtain the generating function for this problem. Finally we establish the analyticity of the generating function.     

A generalized Shimura correspondence for newforms

We associate a set of half integral weight forms to an integral weight newform of odd level. We prove an explicit identity relating the central values of the twist L-functions of the newform to the Fourier coefficients of the half integral weight forms.     

A p-adic Simpson correspondence

For curves over a p-adic field we construct an equivalence between the category of Higgs-bundles and that of “generalised representation” of the etale fundamental group. The definition of “generalised representations” uses p-adic Hodge theory and almost etale coverings, and it includes usual representations which form a full subcategory. The equivalence depends on the choice of an exponential function for the multiplicative group.     

A parametric approach to correspondence analysis

We compare correspondence analysis (CA) and the alternative approach using Hellinger distance (HD), for representing categorical data in a contingency table. As both methods may be appropriate, we introduce a parameter and define a generalized version of correspondence analysis (GCA) which contains CA and HD as particular cases. Comparison with alternative approaches are performed. We propose a coefficient which globally measures the similarity between CA and GCA, which can be decomposed into several components, one component for each principal dimension, indicating the contribution of the dimensions on the difference between both representations. Two criteria for choosing the best value of the parameter are proposed.