# Definition:Poisson Bracket

## Definition

Let

$\map A {x, \mathbf y, \mathbf p}: \R^{2n+1} \to \R$,
$\map B {x, \mathbf y, \mathbf p}: \R^{2n+1} \to \R$, $n \in \N$

be real functions, dependent on canonical variables.

The Poisson Bracket of functions $A$ and $B$ is defined as:

$\displaystyle \sqbrk {A, B} := \sum_{i \mathop = 1}^n \paren {\frac {\partial A} {\partial y_i} \frac {\partial B} {\partial p_i} - \frac {\partial B} {\partial y_i} \frac {\partial A} {\partial p_i} }$

where the notation $\dfrac {\partial A} {\partial y_i}$ denotes partial differentiation.

## Source of Name

This entry was named for Siméon-Denis Poisson.