NF weak partition development: AlphaFocusedSupport.
Small proof combinators for expectation-guided alpha certificates. They keep generated wrappers from repeating dependent equality transport and Finset membership plumbing at every opaque formal subtree.
theorem
NFChoice.DefinitionLeaves.AlphaFocusedSupport.reflOn_nil
(support : Finset SemanticCore.Var)
:
AlphaTransport.ReflOn [] support
Every free variable has a reflexive alpha certificate in the empty binder environment.
theorem
NFChoice.DefinitionLeaves.AlphaFocusedSupport.ReflOn.cons_of_not_mem
{env : AlphaTransport.BinderEnv}
{support : Finset SemanticCore.Var}
{left right : SemanticCore.Var}
(hleft : left ∉ support)
(hright : right ∉ support)
(tail : AlphaTransport.ReflOn env support)
:
AlphaTransport.ReflOn ((left, right) :: env) support
Add a genuinely renamed binder pair when neither endpoint occurs in the support.
theorem
NFChoice.DefinitionLeaves.AlphaFocusedSupport.freshVar_not_mem_of_subset
{small large : Finset SemanticCore.Var}
(offset : ℕ)
(hsub : small ⊆ large)
:
ReplaySupport.freshVar large offset ∉ small
Freshness descends along an explicitly supplied support inclusion.
theorem
NFChoice.DefinitionLeaves.AlphaFocusedSupport.subset_erase_of_subset_of_not_mem
{small large : Finset SemanticCore.Var}
{binder : SemanticCore.Var}
(hsub : small ⊆ large)
(hnot : binder ∉ small)
:
small ⊆ large.erase binder
Insert a known subset beneath an erasure whose binder is absent from it.