  We provide a cross-check of AdS/CFT and a-charge maximization for a four
dimensional $N$=1 SCFT with irrational R-charges. The gauge theory is the low
energy effective theory of N D3-branes at the tip of the complex cone over the
first del Pezzo surface. By carefully taking into account the subtle issue of
flavor symmetry breaking at the fixed point, we show, using a-maximization,
that this theory has in fact irrational central charge and R-charges. Our
results perfectly match with those inherited from the recently discovered
supergravity dual background. Along analogous lines, we make novel predictions
for the still unknown AdS dual of the quiver theory for the second del Pezzo
surface. This should flow to a SCFT with irrational charges, too. All of our
results differ from previous findings in the literature and outline interesting
subtleties in a-maximization and AdS/CFT techniques overlooked in the past.
