A family of well known problems on graphs includingthe shortest path problem and the data flow analysis problem can be uniformly formulated as a fixed-point problem on graphs. We specify this problem and its solution algorithm in a highly abstract manner, fully exploiting the parameterized module construct of CafeOBJ, an algebraic specification language. The objective of our research is to explore effectiveness of formal methods applying them not just to safety critical specific programs but to general problems covering wide range of applications.