Nuprl Lemma : discrete-sigma-equiv
∀A:Type. ∀B:A ⟶ Type. ∀X:j⊢.  {X ⊢ _:Equiv(Σ discr(A) discrete-family(A;a.B[a]);discr(a:A × B[a]))}
Proof
Definitions occuring in Statement : 
discrete-family: discrete-family(A;a.B[a])
, 
cubical-equiv: Equiv(T;A)
, 
discrete-cubical-type: discr(T)
, 
cubical-sigma: Σ A B
, 
cubical-term: {X ⊢ _:A}
, 
cubical_set: CubicalSet
, 
so_apply: x[s]
, 
all: ∀x:A. B[x]
, 
function: x:A ⟶ B[x]
, 
product: x:A × B[x]
, 
universe: Type
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
discrete-family: discrete-family(A;a.B[a])
, 
cc-snd: q
, 
cc-fst: p
, 
csm-comp: G o F
, 
csm-adjoin: (s;u)
, 
csm-ap-type: (AF)s
, 
compose: f o g
, 
csm-ap: (s)x
, 
pi2: snd(t)
, 
subtype_rel: A ⊆r B
, 
uimplies: b supposing a
, 
squash: ↓T
, 
prop: ℙ
, 
true: True
, 
discrete-cubical-type: discr(T)
, 
cubical-lam: cubical-lam(X;b)
, 
cubical-app: app(w; u)
, 
cubical-lambda: (λb)
, 
cube-context-adjoin: X.A
, 
discrete-pair-inv: discrete-pair-inv(X;b)
, 
discrete-pair: discrete-pair(p)
, 
cubical-pair: cubical-pair(u;v)
, 
cubical-snd: p.2
, 
cubical-fst: p.1
, 
cubical-term-at: u(a)
, 
cc-adjoin-cube: (v;u)
, 
csm-ap-term: (t)s
, 
pi1: fst(t)
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
fiber-member: fiber-member(p)
, 
fiber-point: fiber-point(t;c)
Lemmas referenced : 
cubical_set_wf, 
istype-universe, 
cubical-sigma-p, 
cubical-sigma_wf, 
discrete-cubical-type_wf, 
discrete-family_wf, 
csm-discrete-cubical-type, 
discrete-pair_wf, 
cube-context-adjoin_wf, 
cubical_set_cumulativity-i-j, 
cubical-type-cumulativity2, 
cc-snd_wf, 
csm-discrete-family, 
cubical-term-eqcd, 
discrete-pair-inv_wf, 
csm-discrete-sigma, 
cc-fst_wf, 
path-type_wf, 
squash_wf, 
true_wf, 
istype-cubical-term, 
cubical-type_wf, 
csm-ap-type_wf, 
cubical-refl_wf, 
I_cube_wf, 
fset_wf, 
nat_wf, 
cubical-term-equal, 
cubical_type_at_pair_lemma, 
I_cube_pair_redex_lemma, 
cubical-fiber_wf, 
csm-ap-term_wf, 
cubical-fun_wf, 
cubical-lam_wf, 
csm-cubical-fun, 
csm-cubical-fiber, 
equal-fiber-discrete, 
fiber-point_wf, 
csm-fiber-point, 
fiber-discrete-equal, 
fiber-member_wf, 
equal_wf, 
discrete-pair-injection, 
cubical-term_wf, 
cubical-term-at_wf, 
discrete-pair-inv-property, 
cubical-fst-pair, 
equiv-witness_wf, 
cubical-lambda_wf, 
contractible-type_wf, 
contr-witness_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
universeIsType, 
thin, 
instantiate, 
introduction, 
extract_by_obid, 
hypothesis, 
functionIsType, 
hypothesisEquality, 
inhabitedIsType, 
sqequalHypSubstitution, 
isectElimination, 
universeEquality, 
dependent_functionElimination, 
sqequalRule, 
lambdaEquality_alt, 
applyEquality, 
Error :memTop, 
because_Cache, 
equalityTransitivity, 
equalitySymmetry, 
independent_isectElimination, 
hyp_replacement, 
cumulativity, 
productEquality, 
imageElimination, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
functionExtensionality, 
productElimination, 
dependent_pairEquality_alt, 
equalityIstype, 
independent_functionElimination, 
dependent_set_memberEquality_alt, 
independent_pairFormation, 
productIsType, 
applyLambdaEquality, 
setElimination, 
rename
Latex:
\mforall{}A:Type.  \mforall{}B:A  {}\mrightarrow{}  Type.  \mforall{}X:j\mvdash{}.    \{X  \mvdash{}  \_:Equiv(\mSigma{}  discr(A)  discrete-family(A;a.B[a]);discr(a:A  \mtimes{}  B[a]))\}
Date html generated:
2020_05_20-PM-03_41_58
Last ObjectModification:
2020_04_20-PM-06_17_22
Theory : cubical!type!theory
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