We are going to consider the functional inequality f(x+y)−f(x)−f(y)≥ϕ(x,y), x,y∈X, where (X,+) is an abelian
group, and ϕ:X×X→ℝ and f:X→ℝ are unknown mappings. In particular, we will give conditions
which force biadditivity and symmetry of ϕ and the
representation f(x)=(1/2)ϕ(x,x)+a(x) for x∈X, where
a is an additive function. In the present paper, we continue and
develop our earlier studies published by the
author (2004).