 Many existential theorems in classical mathematics have a constructive analogue in which the existential statement is replaced by a statement about approximations. We saw an example of this, the intermediate value theorem, in the section on weak counterexamples above. Large parts of mathematics can be recovered constructively in a similar way. The reason not to treat them any further here is that the focus in this entry is on those aspects of intuitionism that set it apart from other constructive branches of mathematics. For a thorough treatment of constructivism the reader is referred to the corresponding entry in this encyclopedia.