Nuprl Lemma : quotient-of-quotient
∀T:Type. ∀R:T ⟶ T ⟶ ℙ.
  (EquivRel(T;x,y.x R y)
  
⇒ (∀Q:(x,y:T//(x R y)) ⟶ (x,y:T//(x R y)) ⟶ ℙ
        (EquivRel(x,y:T//(x R y);u,v.u Q v) 
⇒ u,v:x,y:T//(x R y)//(u Q v) ≡ x,y:T//(x Q y))))
Proof
Definitions occuring in Statement : 
equiv_rel: EquivRel(T;x,y.E[x; y])
, 
quotient: x,y:A//B[x; y]
, 
ext-eq: A ≡ B
, 
prop: ℙ
, 
infix_ap: x f y
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
function: x:A ⟶ B[x]
, 
universe: Type
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
so_lambda: λ2x y.t[x; y]
, 
prop: ℙ
, 
subtype_rel: A ⊆r B
, 
so_apply: x[s1;s2]
, 
uimplies: b supposing a
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
istype: istype(T)
, 
ext-eq: A ≡ B
, 
and: P ∧ Q
, 
quotient: x,y:A//B[x; y]
, 
infix_ap: x f y
, 
guard: {T}
Lemmas referenced : 
equiv-on-quotient, 
quotient_wf, 
infix_ap_wf, 
subtype_rel_dep_function, 
subtype_quotient, 
equal-wf-base, 
quotient_subtype_quotient, 
subtype_rel_self, 
equiv_rel_wf, 
quotient-member-eq
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :lambdaFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
hypothesisEquality, 
independent_functionElimination, 
hypothesis, 
isectElimination, 
because_Cache, 
sqequalRule, 
Error :lambdaEquality_alt, 
instantiate, 
cumulativity, 
universeEquality, 
applyEquality, 
Error :inhabitedIsType, 
independent_isectElimination, 
functionEquality, 
functionExtensionality, 
Error :universeIsType, 
independent_pairFormation, 
pointwiseFunctionalityForEquality, 
pertypeElimination, 
productElimination, 
equalityTransitivity, 
equalitySymmetry, 
Error :equalityIsType1, 
productEquality, 
Error :functionIsType, 
hyp_replacement
Latex:
\mforall{}T:Type.  \mforall{}R:T  {}\mrightarrow{}  T  {}\mrightarrow{}  \mBbbP{}.
    (EquivRel(T;x,y.x  R  y)
    {}\mRightarrow{}  (\mforall{}Q:(x,y:T//(x  R  y))  {}\mrightarrow{}  (x,y:T//(x  R  y))  {}\mrightarrow{}  \mBbbP{}
                (EquivRel(x,y:T//(x  R  y);u,v.u  Q  v)  {}\mRightarrow{}  u,v:x,y:T//(x  R  y)//(u  Q  v)  \mequiv{}  x,y:T//(x  Q  y))))
Date html generated:
2019_06_20-PM-00_33_09
Last ObjectModification:
2018_09_30-PM-00_36_21
Theory : quot_1
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