Loop invariants play a very important role in proving correctness of
programs. In this paper, we address the problem of generating invariants of
polynomial loop programs. We present a new approach, for generating polynomial
equation invariants of polynomial loop programs through computing vanishing
ideals of sample points. We apply rational function interpolation, based on
early termination technique, to generate invariants of loop programs with
symbolic initial values. Our approach avoids first-order quantifier elimination
and cylindrical algebraic decomposition(CAD).
Let $G=(V,E)$ be a simple graph without isolated vertices. A set $S\subseteq
V$ is a paired-dominating set if every vertex in $V-S$ has at least one
neighbor in $S$ and the subgraph induced by $S$ contains a perfect matching. In
this paper, we present a linear-time algorithm to determine whether a given
vertex in a block graph is contained in all its minimum paired-dominating sets.