Reification (knowledge representation)
Reification in knowledge representation involves the representation of factual assertions, that are referred to by other assertions; which might then be manipulated in some way. e.g., to compare logical assertions from different witnesses in order to determine their credibility.
The message "John is six feet tall" is an assertion involving truth, that commits the speaker to its factuality, whereas the reified statement, "Mary reports that John is six feet tall" defers such commitment to Mary. In this way, the statements can be incompatible without creating contradictions in reasoning. For example the statements "John is six feet tall" and "John is five feet tall" are mutually exclusive (thus, incompatible); but, the statements "Mary reports that John is six feet tall," and "Paul reports that John is five feet tall," are not incompatible, as they both are governed by a conclusive rationale, that either Mary or Paul is (or both of them are), in fact, incorrect.