In the framework for iterative belief revision by Darwiche and Pearl, epistemic states are equipped with a total preorder on possible worlds. Belief changes in this framework not only affect the set of formulas that are considered to be true but the whole preorder. Different postulates were proposed to confine the changes of total preorders. We present Whiwap, a tool which allows the user to enter a belief change with a propositional formula ↵, in particular to specify the total preorder of the

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... prior and the posterior state and the models of ↵. Whiwap checks whether the entered belief change fulfils certain postulates or not. Common belief change postulates for revision and contraction are implemented.