2-Spin System Quick Notes
SettingConfiguration : A configuration of graph is a map such as:
\begin{aligned}
\sigma: V &\to 2^V\\
u&\mapsto \{+,-\}
\end{aligned}Partition Function: For graph , define its partition function as
Z_G(\beta, \gamma, \lambda) = \sum_{\sigma} \beta^{m_{++}}\gamma^{m_{--}}\lambda^{n_+}where is the number of edges between two vertices pinned to , is the number of vertices pinned to , and we sum over all possible configurations.
Initially, we wonder when there exsits a polynomial time ...