Self-dual rational lattice

A rational lattice is self-dual iff it is its own dual lattice, or equivalently it is integral and unimodular. #m/def/geo

Proof

Note for a unimodular integral matrix we have .

Let be a basis matrix for so that , so the basis matrix of is . Now assuming is unimodular, so is and we have

as required.

#state/tidy | #lang/en | #SemBr