[CategoryRefactoring/RefactoringLanguage]
See Bill Murphy and Martin Fowler's page at http://www.refactoring.com/catalog/reverseConditional.html
This refactoring pattern appears to be a subset of RefactorNegateIf.
Related:
- ConditionalProbability
- http://www.richland.edu/james/lecture/m170/ch05-cnd.html