This paper surveys some results of the following type: “If a linear program and some derived programs have integral solutions, so does its dual.” Several well-known minimax theorems in combinatorics can be derived from such general principles. Similar principles can be proved if integrality is replaced by a condition of the least common denominator of the entries of a solution. An analogy between Tutte's 1-factor-theorem and the Lucchesi-Younger Theorem on disjoint directed cuts is pointed out.
ASJC Scopus subject areas
- Discrete Mathematics and Combinatorics