Consider a information model where each record is represented by an immutable tuple. This tuple in this context is called a fact.
Example of a fact:
('john', 'age', 18, true)
In this representation, the subject (or entity) 'john' has a value of '18' associated with the attribute 'age'.
To represent a deletion (or retraction) of information, the fourth element of the tuple can be 'false' to indicate that the corresponding entity's attribute no longer has that value.