Boundary data and the complete transverse product ledger

Every Lagrangian relation has this form. Indeed, let $W$ be its projection onto the $a$-space. The vertical part is $W^{\perp }$ in the $Nb$-variable, and the remaining graph is Hermitian on $W$. This is the finite-dimensional relation version of the usual $U(d)$ parametrization.

For $\beta =0$, only $n=0$ is deficient and

Its extensions are Friedrichs or

denoted ${\mathsf{L}}_L$.