코스트카 수 (Kostka number)
개요
- 코스트카 수(Kostka number) $K_{\lambda\mu}$ : 형태가 $\lambda$이고 weight이 $\mu$인 준표준 영 태블로의 수
- 슈르 다항식(Schur polynomial) $s_{\lambda}(\bar{x})$ 을 단항 대칭 다항식 (monomial symmetric polynomial) $m_{\mu}(\bar{x})$의 선형결합으로 표현할 때 다음을 얻는다
\[s_\lambda(\bar{x})= \sum_\mu K_{\lambda\mu}m_\mu(\bar{x}).\ \]
- 군 \(\mathrm{GL}_n(\mathbb{C})\)의 기약표현 $V_{\lambda}$에서 $\mu$에 대응되는 weight space의 차원
예
테이블
- $n=3$라 두고, $\lambda$가 4의 분할로 주어지는 경우, 슈르 다항식 $s_{\lambda}$와 단항 대칭 다항식 $m_{\lambda}$는 다음과 같은 표로 주어진다
\begin{array}{c|c|c} \lambda & s_{\lambda } & m_{\lambda } \\ \hline (4) & x_1^4+x_2 x_1^3+x_3 x_1^3+x_2^2 x_1^2+x_3^2 x_1^2+x_2 x_3 x_1^2+x_2^3 x_1+x_3^3 x_1+x_2 x_3^2 x_1+x_2^2 x_3 x_1+x_2^4+x_3^4+x_2 x_3^3+x_2^2 x_3^2+x_2^3 x_3 & x_1^4+x_2^4+x_3^4 \\ (3,1) & x_2 x_1^3+x_3 x_1^3+x_2^2 x_1^2+x_3^2 x_1^2+2 x_2 x_3 x_1^2+x_2^3 x_1+x_3^3 x_1+2 x_2 x_3^2 x_1+2 x_2^2 x_3 x_1+x_2 x_3^3+x_2^2 x_3^2+x_2^3 x_3 & x_2 x_1^3+x_3 x_1^3+x_2^3 x_1+x_3^3 x_1+x_2 x_3^3+x_2^3 x_3 \\ (2,2) & x_2^2 x_1^2+x_3^2 x_1^2+x_2 x_3 x_1^2+x_2 x_3^2 x_1+x_2^2 x_3 x_1+x_2^2 x_3^2 & x_1^2 x_2^2+x_3^2 x_2^2+x_1^2 x_3^2 \\ (2,1,1) & x_2 x_3 x_1^2+x_2 x_3^2 x_1+x_2^2 x_3 x_1 & x_2 x_3 x_1^2+x_2 x_3^2 x_1+x_2^2 x_3 x_1 \\ (1,1,1,1) & 0 & 0 \\ \end{array}
코스트카 수의 계산
$$ \begin{align} s_{(4)}(x_1,x_2,x_3) & =x_1^4+x_2 x_1^3+x_3 x_1^3+x_2^2 x_1^2+x_3^2 x_1^2+x_2 x_3 x_1^2+x_2^3 x_1+x_3^3 x_1+x_2 x_3^2 x_1+x_2^2 x_3 x_1+x_2^4+x_3^4+x_2 x_3^3+x_2^2 x_3^2+x_2^3 x_3 \\ & = (x_1^4+x_2^4+x_3^4)+(x_2 x_1^3+x_3 x_1^3+x_2^3 x_1+x_3^3 x_1+x_2 x_3^3+x_2^3 x_3)+(x_1^2 x_2^2+x_3^2 x_2^2+x_1^2 x_3^2)+(x_2 x_3 x_1^2+x_2 x_3^2 x_1+x_2^2 x_3 x_1)\\ & = m_{(4)}(x_1,x_2,x_3)+m_{(3,1)}(x_1,x_2,x_3)+m_{(2,2)}(x_1,x_2,x_3)+m_{(2,1,1)}(x_1,x_2,x_3) \\ s_{(3,1)}(x_1,x_2,x_3) & =x_1^3 x_2+x_1^2 x_2^2+x_1 x_2^3+x_1^3 x_3+2 x_1^2 x_2 x_3+2 x_1 x_2^2 x_3+x_2^3 x_3+x_1^2 x_3^2+2 x_1 x_2 x_3^2+x_2^2 x_3^2+x_1 x_3^3+x_2 x_3^3 \\ & = (x_1^3 x_2+x_1 x_2^3+x_1^3 x_3+x_2^3 x_3+x_1 x_3^3+x_2 x_3^3)+(x_1^2 x_2^2+x_1^2 x_3^2+x_2^2 x_3^2)+2(x_1^2 x_2 x_3+x_1 x_2^2 x_3+x_1 x_2 x_3^2)\\ & = m_{(3,1)}(x_1,x_2,x_3)+m_{(2,2)}(x_1,x_2,x_3)+2m_{(2,1,1)}(x_1,x_2,x_3) \\ s_{(2,2)}(x_1,x_2,x_3) & = x_2^2 x_1^2+x_3^2 x_1^2+x_2 x_3 x_1^2+x_2 x_3^2 x_1+x_2^2 x_3 x_1+x_2^2 x_3^2 \\ & =(x_1^2 x_2^2+x_1^2 x_3^2+x_2^2 x_3^2)+(x_1^2 x_2 x_3+x_1 x_2^2 x_3+x_1 x_2 x_3^2)\\ & = m_{(2,2,0)}(x_1,x_2,x_3)+m_{(2,1,1)}(x_1,x_2,x_3) \\ s_{(2,1,1)}(x_1,x_2,x_3) & = x_2 x_3 x_1^2+x_2 x_3^2 x_1+x_2^2 x_3 x_1 \\ & =(x_1^2 x_2 x_3+x_1 x_2^2 x_3+x_1 x_2 x_3^2)\\ & = m_{(2,1,1)}(x_1,x_2,x_3) \end{align} $$
\begin{array}{c|cccc}
\lambda\backslash \mu & (4) & (3,1) & (2,2) & (2,1,1) \\
\hline
(4) & 1 & 1 & 1 & 1 \\
(3,1) & 0 & 1 & 1 & 2 \\
(2,2) & 0 & 0 & 1 & 1 \\
(2,1,1) & 0 & 0 & 0 & 1 \\
\end{array}
테이블
$n=1$
\begin{array}{c|c} \text{} & \{1\} \\ \hline \{1\} & 1 \\ \end{array}
$n=2$
\begin{array}{c|cc} \text{} & \{2\} & \{1,1\} \\ \hline \{2\} & 1 & 1 \\ \{1,1\} & 0 & 1 \\ \end{array}
$n=3$
\begin{array}{c|ccc} \text{} & \{3\} & \{2,1\} & \{1,1,1\} \\ \hline \{3\} & 1 & 1 & 1 \\ \{2,1\} & 0 & 1 & 2 \\ \{1,1,1\} & 0 & 0 & 1 \\ \end{array}
$n=4$
\begin{array}{c|cccc} \text{} & \{4\} & \{3,1\} & \{2,2\} & \{2,1,1\} & \{1,1,1,1\} \\ \hline \{4\} & 1 & 1 & 1 & 1 & 1 \\ \{3,1\} & 0 & 1 & 1 & 2 & 3 \\ \{2,2\} & 0 & 0 & 1 & 1 & 2 \\ \{2,1,1\} & 0 & 0 & 0 & 1 & 3 \\ \{1,1,1,1\} & 0 & 0 & 0 & 0 & 1 \\ \end{array}
$n=5$
\begin{array}{c|ccccccc} \text{} & \{5\} & \{4,1\} & \{3,2\} & \{3,1,1\} & \{2,2,1\} & \{2,1,1,1\} & \{1,1,1,1,1\} \\ \hline \{5\} & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ \{4,1\} & 0 & 1 & 1 & 2 & 2 & 3 & 4 \\ \{3,2\} & 0 & 0 & 1 & 1 & 2 & 3 & 5 \\ \{3,1,1\} & 0 & 0 & 0 & 1 & 1 & 3 & 6 \\ \{2,2,1\} & 0 & 0 & 0 & 0 & 1 & 2 & 5 \\ \{2,1,1,1\} & 0 & 0 & 0 & 0 & 0 & 1 & 4 \\ \{1,1,1,1,1\} & 0 & 0 & 0 & 0 & 0 & 0 & 1 \\ \end{array}
메모
- http://www.math.cornell.edu/~rassart/pub/KLRslides.pdf
- http://math.stackexchange.com/questions/17891/why-is-a-general-formula-for-kostka-numbers-unlikely-to-exist
관련된 항목들
매스매티카 파일 및 계산 리소스
- https://docs.google.com/file/d/0B8XXo8Tve1cxcjkzaUVqdnRnUm8/edit
- http://mathematica.stackexchange.com/questions/22852/looking-for-a-package-regarding-schur-polynomials-and-kostka-numbers
관련논문
- Kirillov, Anatol N., Anne Schilling, and Mark Shimozono. 1999. “Various Representations of the Generalized Kostka Polynomials.” Séminaire Lotharingien de Combinatoire 42: Art. B42j, 19 pp. (electronic). http://www.emis.de/journals/SLC/wpapers/s42schil.pdf