Nuprl Lemma : context-subset_functionality
∀[Gamma:j⊢]. ∀[a,b:{Gamma ⊢ _:𝔽}].  (Gamma ⊢ (a ⇐⇒ b) ⇒ {Gamma, a ⊢ _} ≡ {Gamma, b ⊢ _})
Proof
Definitions occuring in Statement : 
face-term-iff: Gamma ⊢ (phi ⇐⇒ psi), 
context-subset: Gamma, phi, 
face-type: 𝔽, 
cubical-term: {X ⊢ _:A}, 
cubical-type: {X ⊢ _}, 
cubical_set: CubicalSet, 
ext-eq: A ≡ B, 
uall: ∀[x:A]. B[x], 
implies: P ⇒ Q
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
implies: P ⇒ Q, 
face-term-iff: Gamma ⊢ (phi ⇐⇒ psi), 
and: P ∧ Q, 
ext-eq: A ≡ B, 
uimplies: b supposing a, 
face-term-implies: Gamma ⊢ (phi ⇒ psi), 
prop: ℙ, 
subtype_rel: A ⊆r B
Lemmas referenced : 
context-subset-subtype, 
face-term-iff_wf, 
cubical-term_wf, 
face-type_wf, 
cubical_set_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
introduction, 
cut, 
lambdaFormation_alt, 
sqequalHypSubstitution, 
productElimination, 
thin, 
independent_pairFormation, 
extract_by_obid, 
isectElimination, 
hypothesisEquality, 
independent_isectElimination, 
hypothesis, 
because_Cache, 
universeIsType, 
instantiate, 
sqequalRule, 
lambdaEquality_alt, 
dependent_functionElimination, 
independent_pairEquality, 
axiomEquality, 
functionIsTypeImplies, 
inhabitedIsType, 
isect_memberEquality_alt, 
isectIsTypeImplies
Latex:
\mforall{}[Gamma:j\mvdash{}].  \mforall{}[a,b:\{Gamma  \mvdash{}  \_:\mBbbF{}\}].    (Gamma  \mvdash{}  (a  \mLeftarrow{}{}\mRightarrow{}  b)  {}\mRightarrow{}  \{Gamma,  a  \mvdash{}  \_\}  \mequiv{}  \{Gamma,  b  \mvdash{}  \_\})
Date html generated:
2020_05_20-PM-02_51_36
Last ObjectModification:
2020_04_06-AM-10_32_20
Theory : cubical!type!theory
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