Complex sentence: In theoretical physics, the Peierls bracket is an equivalent description of the Poisson bracket that directly follows from the action and does not require the canonical coordinates and their canonical momenta to be defined in advance.
Split into simpler sentences: In theoretical physics, the Peierls bracket is an equivalent description of the Poisson bracket. It directly follows from the action and does not require the canonical coordinates and their canonical momenta to be defined in advance.