Nuprl Lemma : presheaf-eta
∀[C:SmallCategory]. ∀[X:ps_context{j:l}(C)]. ∀[A:{X ⊢ _}]. ∀[B:{X.A ⊢ _}]. ∀[w:{X ⊢ _:ΠA B}].
  ((λapp((w)p; q)) = w ∈ {X ⊢ _:ΠA B})
Proof
Definitions occuring in Statement : 
presheaf-app: app(w; u)
, 
presheaf-lambda: (λb)
, 
presheaf-pi: ΠA B
, 
psc-snd: q
, 
psc-fst: p
, 
psc-adjoin: X.A
, 
pscm-ap-term: (t)s
, 
presheaf-term: {X ⊢ _:A}
, 
presheaf-type: {X ⊢ _}
, 
ps_context: __⊢
, 
uall: ∀[x:A]. B[x]
, 
equal: s = t ∈ T
, 
small-category: SmallCategory
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
subtype_rel: A ⊆r B
, 
psc-snd: q
, 
psc-fst: p
, 
pscm-ap-term: (t)s
, 
presheaf-app: app(w; u)
, 
presheaf-lambda: (λb)
, 
presheaf-pi: ΠA B
, 
pi1: fst(t)
, 
pscm-ap: (s)x
, 
presheaf-term: {X ⊢ _:A}
, 
all: ∀x:A. B[x]
, 
presheaf-pi-family: presheaf-pi-family(C; X; A; B; I; a)
, 
squash: ↓T
, 
uimplies: b supposing a
, 
true: True
, 
prop: ℙ
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
rev_implies: P 
⇐ Q
, 
implies: P 
⇒ Q
, 
psc-adjoin-set: (v;u)
, 
pi2: snd(t)
, 
presheaf-type-at: A(a)
Lemmas referenced : 
presheaf-term_wf, 
presheaf-pi_wf, 
presheaf-type_wf, 
psc-adjoin_wf, 
small-category-cumulativity-2, 
ps_context_cumulativity2, 
presheaf-type-cumulativity2, 
ps_context_wf, 
small-category_wf, 
presheaf_type_at_pair_lemma, 
I_set_wf, 
cat-ob_wf, 
presheaf-type-at_wf, 
psc-restriction_wf, 
cat-arrow_wf, 
psc-adjoin-set_wf, 
presheaf-type-ap-morph_wf, 
cat-comp_wf, 
subtype_rel-equal, 
psc-restriction-comp, 
psc-adjoin-set-restriction, 
equal_wf, 
squash_wf, 
true_wf, 
istype-universe, 
subtype_rel_self, 
iff_weakening_equal, 
presheaf_type_ap_morph_pair_lemma, 
cat-id_wf, 
psc-restriction-id, 
cat-comp-ident1, 
presheaf-term-equal
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
introduction, 
cut, 
equalitySymmetry, 
hypothesis, 
universeIsType, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
sqequalRule, 
isect_memberEquality_alt, 
axiomEquality, 
isectIsTypeImplies, 
inhabitedIsType, 
instantiate, 
applyEquality, 
functionExtensionality_alt, 
setElimination, 
rename, 
dependent_functionElimination, 
Error :memTop, 
applyLambdaEquality, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
dependent_set_memberEquality_alt, 
functionIsType, 
because_Cache, 
equalityIstype, 
independent_isectElimination, 
lambdaEquality_alt, 
natural_numberEquality, 
equalityTransitivity, 
universeEquality, 
productElimination, 
independent_functionElimination, 
hyp_replacement, 
functionExtensionality
Latex:
\mforall{}[C:SmallCategory].  \mforall{}[X:ps\_context\{j:l\}(C)].  \mforall{}[A:\{X  \mvdash{}  \_\}].  \mforall{}[B:\{X.A  \mvdash{}  \_\}].  \mforall{}[w:\{X  \mvdash{}  \_:\mPi{}A  B\}].
    ((\mlambda{}app((w)p;  q))  =  w)
Date html generated:
2020_05_20-PM-01_33_42
Last ObjectModification:
2020_04_02-PM-06_32_30
Theory : presheaf!models!of!type!theory
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