A sufficient and necessary consition for a general (2,1,0,0) type algebra (L,→,*,0,1)
to be a lattice implication algebra is presented. It is proved that in a finite chain and in a non-linear
four-element lattice there exists only one lattice implication algebra, but no implication algebra in a
non-linear five-element lattice. This provides the foundation for further study of the structure of
lattice implication algebra that is composed of linguistic true values.