Erratum to "Forcing in proof theory":
At the end of Section 2.1, I originally stated that the Kuroda translation of a formula can be proved equivalent to its double-negation translation in minimal logic. This is not true; proving the equivalence can require intuitionistic logic. Thus provability in minimal logic should be replaced by provability in intuitionistic logic in Proposition 2.4. This has been corrected in the online version.