A Symbolic-Numeric Approach to Minimal Polynomial Logic and to Rule Based Expert Systems that Use this Logic E. Roanes-Lozano, Luis M. Laita and E. Roanes-Macias We had previously developed an algebraic model of classic Boolean and modal many-valued logics. A similar approach, also using computer algebra techniques (Groebner bases) and oriented to perform effective calculus in a certain continuous logic: minimal polynomial logic (MPL), and also to perform knowledge extraction and to check consistency in rule based expert systems (RBES) whose underlying logic is MPL, is presented. The implementation has been developed in the computer algebra system Maple. The presentation will be illustrated with examples of simple RBES.