Kyungyong Lee

  1. On cluster variables of rank two acyclic cluster algebras.

    Authors: Kyungyong Lee
    Subjects: Combinatorics
    Abstract

    In this note, we find an explicit formula for the Laurent expression of
    cluster variables of coefficient-free rank two cluster algebras associated with
    the matrix $\left(\begin{array}{cc} 0 & c\\-c & 0 \end{array}\right)$, and show
    that a large number of coefficients are non-negative. As a corollary, we obtain
    an explicit expression for the Euler-Poincar\'{e} characteristics of the
    corresponding quiver Grassmannians.

  2. Virtual Private Overlays: Secure Group Commounication in NAT-Constrained Environments.

    Authors: Kyungyong Lee, David Isaac Wolinsky, Tae Woong Choi, P. Oscar Boykin, Renato Figueiredo
    Subjects: Networking and Internet Architecture
    Abstract

    Structured P2P overlays provide a framework for building distributed
    applications that are self-configuring, scalable, and resilient to node
    failures.

  3. Notes on a minimal set of generators for the radical ideal defining the diagonal locus of $(\C^2)^n$.

    Authors: Kyungyong Lee, Li Li
    Subjects: Combinatorics
    Abstract

    We develop several techniques for the study of the radical ideal $I$ defining
    the diagonal locus of $(\C^2)^n$. Using these techniques, we give combinatorial
    construction of generators for $I$ of certain bi-degrees.

  4. Notes on a minimal set of generators for the radical ideal defining the diagonal locus of $(\C^2)^n$.

    Authors: Kyungyong Lee, Li Li
    Subjects: Combinatorics
    Abstract

    We develop several techniques for the study of the radical ideal $I$ defining
    the diagonal locus of $(\C^2)^n$. Using these techniques, we give combinatorial
    construction of generators for $I$ of certain bi-degrees.

  5. $q,t$-Catalan numbers and generators for the radical ideal defining the diagonal locus of $(\C^2)^n$.

    Authors: Kyungyong Lee, Li Li
    Subjects: Combinatorics
    Abstract

    Let $I$ be the ideal generated by alternating polynomials in two sets of $n$
    variables. Haiman proved that the $q,t$-Catalan number is the Hilbert series of
    the graded vector space $M(=\bigoplus_{d_1,d_2}M_{d_1,d_2})$ spanned by a
    minimal set of generators for $I$. In this paper we give simple upper bounds on
    $\text{dim}M_{d_1, d_2}$ in terms of partition numbers, and find all bi-degrees
    $(d_1,d_2)$ such that $\dim M_{d_1, d_2}$ achieve the upper bounds. For such
    bi-degrees, we also find explicit bases for $M_{d_1, d_2}$.

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