Alternative to domain wall fermions - art. no. 074504

We define a sparse Hermitian lattice Dirac matrix H coupling 2n+1 Dirac fer mions. When 2n fermions are integrated out the induced action for the last fermion is a rational approximation to the Hermitian overlap Dirac operator . We provide rigorous bounds on the condition number of H and compare them to bounds for the higher dimensional Dirac operator of domain wall fermions . Our main conclusion is that overlap fermions should be taken seriously as a practical alternative to domain wall fermions in the context of numerica l QCD.