  The program dependence graph (PDG) represents data and control dependence
between statements in a program. This paper presents an operational semantics
of program dependence graphs. Since PDGs exclude artificial order of statements
that resides in sequential programs, executions of PDGs are not unique.
However, we identified a class of PDGs that have unique final states of
executions, called deterministic PDGs. We prove that the operational semantics
of control flow graphs is equivalent to that of deterministic PDGs. The class
of deterministic PDGs properly include PDGs obtained from well-structured
programs. Thus, our operational semantics of PDGs is more general than that of
PDGs for well-structured programs, which are already established in literature.
