  Schrijver graphs are vertex-color-critical subgraphs of Kneser graphs having
the same chromatic number. They also share the value of their fractional
chromatic number but Schrijver graphs are not critical for that. Here we
present an induced subgraph of every Schrijver graph that is vertex-critical
with respect to the fractional chromatic number. These subgraphs turn out to be
isomorphic with certain circular complete graphs. We also characterize the
critical edges within this subgraph.
