Balanced bilinear forms and finiteness properties for incidence coalgebras over a field

Let C = IC(X) be the incidence coalgebra of an intervally finite partially ordered set X over a field. We investigate finiteness properties of C. We determine all C*-balanced bilinear forms on C, and we deduce that C is left (or right) quasi-co-Frobenius if and only if C is left (or right) co-Frobenius, and this is equivalent to the order relation on X being the equality