  Fractional (hyper-)graph theory is concerned with the specific problems that
arise when fractional analogues of otherwise integer-valued (hyper-)graph
invariants are considered. The focus of this paper is on fractional edge covers
of hypergraphs. Our main technical result generalizes and unifies previous
conditions under which the size of the support of fractional edge covers is
bounded independently of the size of the hypergraph itself. This allows us to
extend previous tractability results for checking if the fractional hypertree
width of a given hypergraph is $\leq k$ for some constant $k$. We also show how
our results translate to fractional vertex covers.
