What are examples of obversion in logic?

Obversion in logic is a type of immediate inference that transforms a proposition into its equivalent by changing its quality and replacing the predicate with its complement. For example, the statement "All cats are mammals" can be obverted to "No cats are non-mammals." Another example is the statement "Some birds are not sparrows," which can be obverted to "Some birds are non-sparrows." In both cases, the truth value of the original statement is preserved.