This paper presents a symbolic framework for program understanding. The framework makes use of three approaches, each of which has the following conceptual spaces: syntax, semantics, simulation, and pragmatics. The paper starts by focusing on grammars and then progresses via semantics and the automaton theory to program proving, which goal is typical for maintainers. The captured argumentative information helps them to create new logic-based knowledge, in which abstract program concepts are used to connect lower-level representations. A tool, JavaMaster, is used for simulating Java and for proving the results.