New isolated toughness condition for fractional $(g,f,n)$-critical graphs

Let $i(G)$ be the number of isolated vertices in a graph G. The isolated toughness of G is defined as I(G)=∞ if G is complete, and I(G)=min\|S|/i(G-S) : S⊆ V(G),\, i(G-S)≥ 2\ otherwise. We show that G is a frac