Absoluteness
Last updated
Was this helpful?
Last updated
Was this helpful?
In mathematical logic, a formula is said to be absolute if it has the same truth value in each class of structures/models.
Theorems about absoluteness typically establish relationships between the absoluteness of formulas and their syntactic form.
There are two weaker forms of partial absoluteness:
if the truth of a formula in each substructure N of a structure M follows from its truth in M, the formula is downward absolute.
if the truth of a formula in a structure N implies its truth in each structure M extending N, the formula is upward absolute.