⟦ ⟧Double square brackets are often used in mathematical logic and computer science to denote semantic evaluation or interpretation. They can also be used in other contexts where a special type of bracketing is needed, such as denoting intervals or specific operations.
Semantic evaluation of x in logic or computer science.
⟦ x ⟧Denoting a closed interval from a to b.
⟦ a, b ⟧Interpretation or evaluation of the function f at x.
⟦ f(x) ⟧