Manipulation of large-scale combinatorial data is one of the important fundamental technique for web information retrieval, integration, and mining. Recently, we proposed a new approach based on Zero-suppressed BDDs (Binary Decision Diagrams) for efficient database analysis. In this paper, we present VSOP program developed for calculating combinatorial item sets specified by symbolic expressions. Based on ZBDD techniques, VSOP can efficiently handle large-scale sum-of-products expressions with a number of item symbols. VSOP supports not only Boolean set operations but also numerical arithmetic operations based on Valued-Sum-Of-Products algebra, such as addition, subtraction, multiplication, division, numerical comparison, etc. VSOP will facilitate research and development for various database analysis problems.