FFI \(\mathrm{FFI}\) — Type-Qualified Free-For-Instantiation Hygiene Predicate (Fm.FFI, ClassTerm.FFI, AST Constructor: TpFFI)
Metalevel-1 type-qualified syntactic hygiene predicate Fm.FFI((t:X.Expression), x, 𝛗) (qualified by Fm. when its 3rd argument is a formula, or ClassTerm.FFI when its 3rd argument is a class term) asserting that no free variable of term expression t becomes captured when substituted for free occurrences of variable x in 𝛗.
| Field | Mathematical & Kernel Specification (MKTD1 / MKTD2) |
|---|---|
| Symbol |
FFI
\(\mathrm{FFI}\)
|
| Category | Predicate Symbol (Metatheoretic Side-Condition Predicate) |
| SML AST Constructor | Kernel AST Symbol / Sort Constructor in typetheory.ML (Class_p / Truth_p / EXP / UCol) |
| Constructor Arguments | Typed arguments as specified by the Signature / Sort field above |
| Metatype / Signature | X.Expression × Variable × Fm → Bool |
| Binder Status | See Category & Signature above |
| Defining Kernel Entries (ML Labels) | See Related Symbols & Kernel Entries below. |
| LaTeX Form | \mathrm{FFI} |
| How to Understand It | SML AST Constructor: |
| Canonical Law / Usage | Fm.FFI((t:X.Expression), x, 𝛗) |
| Related Symbols & Kernel Entries |