Abstract: The paper presents a historical perspective to the theory of decision diagrams from the first definitions of the trees in mathematics related to the representations of discrete sets to the more recent definitions of different decision trees and related diagrams that are widely used in few areas of computing. Special attention has been paid to the relationships (similarities and differences) between Binary decision diagrams (BDD) and Structurally synthesized binary decision diagrams (SSBDD).
Keywords: Switching theory; logic design; decision diagrams; testing of digital devices.