Both the Beth definability theorem and Craig's lemma (interpolation theorem from now on) deal with the issue of the entanglement, of one language L₁ with another language L₂, that is to say, information transfer - or the lack of such transfer - between the two languages.

The notion of splitting we study looks into this issue. We briefly relate our own results in this area as well as the results of other researchers like Kourousias and Makinson, and Peppas, Chopra and Foo. We do have one new (easy, but possibly important) theorem.