Exactly massless quarks on the lattice

It is suggested that the fermion determinant for a vector-like gauge theory with strictly massless quarks can be represented on the lattice as $\det \frac{1+V}{2}$, where $V=X(X^{†}X{)}^{-1\mathrm{/}2}$ and $X$ is the Wilson-Dirac lattice operator with a negative mass term. There is no undesired doubling and no need for any fine tuning. Several other appealing features of the formula are pointed out.