Application of the Luttinger theorem introduced in section 3.1 implies that, regardless of the route to a FL, if their magnetic moments are quenched then the f-electrons must be counted in the Fermi surface volume [73]. FS studies [74] using magneto-oscillatory techniques such as the de Haas van Alphen (dHvA) effect have verified that this is so. The most straightforward theory [75] for the FS utilizes the LDA band structure, including the f-electrons. A more sophisticated approach includes the f-electrons but renormalizes the ir scattering phase shifts at the FS to be Kondo-like. This procedure gives heavy masses and often makes only a minor perturbation of the original LDA FS [76]. A crucially important theoretical conjecture by Fulde and Zwicknagl [77,78] is that above TK where the f-electron moment is no longer quenched, the f-electrons should now be excluded from the FS volume. This idea is plausible but there is no proof having the rigor of the Luttinger theorem and in any case it would not hold experimentally if in fact Kondo physics were irrelevant in the heavy Fermion materials, as some workers propose. This section presents ARPES **data** verifying the Fulde/Zwicknagl conjecture.