International audienceThis chapter argues that the qualifiers of imperfection in geographic information can be reviewed in the highly formalized framework of AGM belief revision in knowledge engineering. It tackles the belief revision methods used for imperfect information, especially Bayesian revision (Bayes' theorem and Jeffrey's rule) and the alternatives in non‐probabilistic formalisms (Dempster's rule of combination in evidence theory, possibilistic conditioning in possibility theory). The chapter shows how the theories about the imperfect representation of spatial objects can be implemented from an operational point of view, to solve the issue of belief revision on available information. It also shows how revision operations may creat...