Nuprl Lemma : csm-contractible-type
∀[X:j⊢]. ∀[A:{X ⊢ _}]. ∀[Z:j⊢]. ∀[s:Z j⟶ X].  ((Contractible(A))s = Z ⊢ Contractible((A)s) ∈ {Z ⊢ _})
Proof
Definitions occuring in Statement : 
contractible-type: Contractible(A), 
csm-ap-type: (AF)s, 
cubical-type: {X ⊢ _}, 
cube_set_map: A ⟶ B, 
cubical_set: CubicalSet, 
uall: ∀[x:A]. B[x], 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
subtype_rel: A ⊆r B, 
cube_set_map: A ⟶ B, 
psc_map: A ⟶ B, 
nat-trans: nat-trans(C;D;F;G), 
cat-ob: cat-ob(C), 
pi1: fst(t), 
op-cat: op-cat(C), 
spreadn: spread4, 
cube-cat: CubeCat, 
fset: fset(T), 
quotient: x,y:A//B[x; y], 
cat-arrow: cat-arrow(C), 
pi2: snd(t), 
type-cat: TypeCat, 
all: ∀x:A. B[x], 
names-hom: I ⟶ J, 
cat-comp: cat-comp(C), 
compose: f o g, 
prop: ℙ, 
squash: ↓T, 
true: True, 
and: P ∧ Q, 
uimplies: b supposing a, 
contractible-type: Contractible(A), 
guard: {T}, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
implies: P ⇒ Q, 
cubical-type: {X ⊢ _}, 
cc-snd: q, 
csm-ap-type: (AF)s, 
cc-fst: p, 
csm-comp: G o F, 
csm-ap: (s)x, 
csm-adjoin: (s;u), 
csm-ap-term: (t)s
Lemmas referenced : 
cube_set_map_wf, 
cubical-type_wf, 
cubical_set_wf, 
csm-ap-comp-type, 
cubical_set_cumulativity-i-j, 
cube-context-adjoin_wf, 
csm-ap-type_wf, 
cubical-type-cumulativity2, 
cc-fst_wf, 
subtype_rel_self, 
equal_wf, 
squash_wf, 
true_wf, 
istype-universe, 
csm-comp_wf, 
csm-ap-type-fst-adjoin, 
subtype_rel-equal, 
csm-cubical-sigma, 
cubical-pi_wf, 
path-type_wf, 
csm-ap-term_wf, 
cc-snd_wf, 
cubical-sigma_wf, 
iff_weakening_equal, 
csm-cubical-pi, 
csm-adjoin_wf, 
csm-adjoin-comp, 
csm-comp-type, 
cubical-term_wf, 
csm-path-type, 
csm-ap-term-snd-adjoin
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
introduction, 
cut, 
hypothesis, 
universeIsType, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
sqequalRule, 
isect_memberEquality_alt, 
axiomEquality, 
isectIsTypeImplies, 
inhabitedIsType, 
instantiate, 
applyEquality, 
because_Cache, 
applyLambdaEquality, 
equalitySymmetry, 
hyp_replacement, 
lambdaEquality_alt, 
imageElimination, 
equalityTransitivity, 
universeEquality, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
Error :memTop, 
dependent_set_memberEquality_alt, 
independent_pairFormation, 
productIsType, 
equalityIstype, 
setElimination, 
rename, 
productElimination, 
independent_isectElimination, 
dependent_functionElimination, 
independent_functionElimination
Latex:
\mforall{}[X:j\mvdash{}].  \mforall{}[A:\{X  \mvdash{}  \_\}].  \mforall{}[Z:j\mvdash{}].  \mforall{}[s:Z  j{}\mrightarrow{}  X].    ((Contractible(A))s  =  Z  \mvdash{}  Contractible((A)s))
Date html generated:
2020_05_20-PM-03_22_52
Last ObjectModification:
2020_04_07-PM-05_05_19
Theory : cubical!type!theory
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