book
Proofs and Refutations
by Imre Lakatos
A classroom dialogue in which a teacher and students argue over Euler's formula for polyhedra, run into one counterexample after another, and act out in miniature how definitions really get stretched and patched to save a theorem. It is Lakatos's case that mathematics grows by conjecture and criticism rather than by deduction from axioms, and still the sharpest book on what a proof is for.






