Low-Degree Curves and Smooth Hilbert Loci on the Fermat Fourfold

For the degree-d Fermat fourfold in complex projective 5-space, and for delta>=2 with d>10delta-6, we describe the integral degree-delta Hilbert locus as a disjoint union of 15d^3 smooth open plane-form spaces. The point classification applies Salberger's diagonal-curve inequality after a minimal-support descent already present in the frozen research aid. The scheme-level extension follows from a three-term Wronskian lemma: the normal bundle of a standard plane has no sections on any integral degree-delta plane curve when d>delta+3, including singular curves. Reznick's published nonstandard conic on X_14 makes the conic cutoff d>=15 sharp. Combining the published degree and genus inequalities also gives a stronger necessary genus bound for nonstandard curves.