Interpolation

A logical construction that, given formulas A and B with A logically entailing B, produces a formula I (the interpolant) that is implied by A, entails B, and mentions only the nonlogical symbols common to A and B.

The insertion of material—words, sentences, passages, marginal notes migrated into the main body, glosses, or other content—into an existing text by later hands, editors, or redactors, such that the text's transmission, authorship claims, chronology, or sense are materially affected.