Journal of Combinatorial Theory Series A ( IF 1.1 ) Pub Date : 2020-07-22 , DOI: 10.1016/j.jcta.2020.105298 Marko Thiel , Nathan Williams
Motivated by the study of simultaneous cores, we give three proofs (in varying levels of generality) that the expected norm of a weight in a highest weight representation of a complex simple Lie algebra is . First, we argue directly using the polynomial method and the Weyl character formula. Second, we relate this problem to the “Winnie-the-Pooh problem” regarding orthogonal decompositions of Lie algebras; although this approach offers the most explanatory power by interpreting the quantity as the eigenvalue for the Casimir element on , it applies only to Cartan types other than A and C. Third, we use the combinatorics of semistandard tableaux to obtain the result in type A. We conclude with computations of many combinatorial cumulants.
中文翻译:
奇怪的期望和小熊维尼问题
通过同时核的研究,我们给出了三个证明(在不同的普遍性水平下),即最大重量表示形式下的预期重量范数 复杂的简单李代数 是 。首先,我们直接使用多项式方法和Weyl字符公式进行争论。其次,我们将此问题与有关李代数正交分解的“维尼小熊维尼问题”联系起来。尽管这种方法通过解释数量提供了最具解释力 作为Casimir元素的特征值 ,它仅适用于A和C以外的Cartan类型。第三,我们使用半标准表格的组合来获得类型A的结果。我们以许多组合累积量的计算得出结论。