Abstract: In this talk, we present some classes of logical structures
from the universal logic standpoint, viz., those of the Tarski- and the
Lindenbaum-types. The characterization theorems for the Tarski- and
two of the four different Lindenbaum-type logical structures have been
proved as well. The separations between the five classes of logical structures,
viz., the four Lindenbaum-types and the Tarski-type have been
established via examples. Finally, we study the logical structures that
are of both Tarski- and a Lindenbaum-type, show their separations, and
end with characterization, adequacy, minimality, and representation theorems
for one of the Tarski-Lindenbaum-type logical structures.