Nuprl Lemma : sigma-path-fst
∀X:j⊢. ∀A:{X ⊢ _}. ∀B:{X.A ⊢ _}. ∀x,y:{X ⊢ _:Σ A B}.  ({X ⊢ _:(Path_Σ A B x y)} 
⇒ {X ⊢ _:(Path_A x.1 y.1)})
Proof
Definitions occuring in Statement : 
path-type: (Path_A a b)
, 
cubical-fst: p.1
, 
cubical-sigma: Σ A B
, 
cube-context-adjoin: X.A
, 
cubical-term: {X ⊢ _:A}
, 
cubical-type: {X ⊢ _}
, 
cubical_set: CubicalSet
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
subtype_rel: A ⊆r B
, 
and: P ∧ Q
, 
cubical-type: {X ⊢ _}
, 
cc-snd: q
, 
cc-fst: p
, 
csm-ap-type: (AF)s
, 
interval-type: 𝕀
, 
csm-comp: G o F
, 
csm-ap: (s)x
, 
constant-cubical-type: (X)
, 
compose: f o g
, 
uimplies: b supposing a
, 
cubical-path-app: pth @ r
, 
true: True
, 
same-cubical-term: X ⊢ u=v:A
, 
squash: ↓T
, 
prop: ℙ
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
Lemmas referenced : 
cubical-term_wf, 
path-type_wf, 
cubical-sigma_wf, 
cubical-type-cumulativity2, 
cubical_set_cumulativity-i-j, 
cube-context-adjoin_wf, 
cubical-type_wf, 
cubical_set_wf, 
path-eta_wf, 
path-type-subtype, 
cubical-sigma-p, 
interval-type_wf, 
term-to-path-wf, 
cubical-fst_wf, 
csm-ap-type_wf, 
cc-fst_wf, 
csm-adjoin_wf, 
csm-comp_wf, 
cc-snd_wf, 
csm-cubical-fst, 
path-eta-1, 
path-eta-0, 
same-cubical-term_wf, 
squash_wf, 
true_wf, 
cubical-path-app-1, 
iff_weakening_equal, 
cubical-path-app-0
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
universeIsType, 
cut, 
thin, 
instantiate, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
applyEquality, 
hypothesis, 
sqequalRule, 
inhabitedIsType, 
because_Cache, 
rename, 
dependent_functionElimination, 
equalitySymmetry, 
dependent_set_memberEquality_alt, 
independent_pairFormation, 
equalityTransitivity, 
productIsType, 
equalityIstype, 
applyLambdaEquality, 
setElimination, 
productElimination, 
lambdaEquality_alt, 
hyp_replacement, 
independent_isectElimination, 
Error :memTop, 
natural_numberEquality, 
imageElimination, 
imageMemberEquality, 
baseClosed, 
independent_functionElimination
Latex:
\mforall{}X:j\mvdash{}.  \mforall{}A:\{X  \mvdash{}  \_\}.  \mforall{}B:\{X.A  \mvdash{}  \_\}.  \mforall{}x,y:\{X  \mvdash{}  \_:\mSigma{}  A  B\}.
    (\{X  \mvdash{}  \_:(Path\_\mSigma{}  A  B  x  y)\}  {}\mRightarrow{}  \{X  \mvdash{}  \_:(Path\_A  x.1  y.1)\})
Date html generated:
2020_05_20-PM-03_25_06
Last ObjectModification:
2020_04_07-PM-04_41_22
Theory : cubical!type!theory
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