Starting with version 1.3, VESD enables to develop the expert system with variables. Relationships between objects or people of the type (? x fact? y), it is a fact associated with 2 variables x and y.

      Example the Fact [Paul is the father of John]. Simple knowledge linking between them relations as the Rule:

      If X is the father of Y and Y is the father of Z then X is the grandfather of Z.

Example: The creation of a fact "is the father of" with 2 variables Name_x is Name_y.