Nuprl Lemma : not-quotient-true
∀[P:ℙ]. (¬⇃(P) 
⇐⇒ ¬P)
Proof
Definitions occuring in Statement : 
quotient: x,y:A//B[x; y]
, 
uall: ∀[x:A]. B[x]
, 
prop: ℙ
, 
iff: P 
⇐⇒ Q
, 
not: ¬A
, 
true: True
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
implies: P 
⇒ Q
, 
not: ¬A
, 
false: False
, 
prop: ℙ
, 
so_lambda: λ2x y.t[x; y]
, 
so_apply: x[s1;s2]
, 
uimplies: b supposing a
, 
rev_implies: P 
⇐ Q
, 
quotient: x,y:A//B[x; y]
, 
cand: A c∧ B
Lemmas referenced : 
trivial-quotient-true, 
istype-universe, 
not_wf, 
quotient_wf, 
true_wf, 
equiv_rel_true, 
false_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
independent_pairFormation, 
Error :lambdaFormation_alt, 
thin, 
sqequalHypSubstitution, 
independent_functionElimination, 
extract_by_obid, 
isectElimination, 
hypothesisEquality, 
hypothesis, 
voidElimination, 
Error :universeIsType, 
cumulativity, 
sqequalRule, 
Error :lambdaEquality_alt, 
Error :inhabitedIsType, 
independent_isectElimination, 
because_Cache, 
productElimination, 
independent_pairEquality, 
dependent_functionElimination, 
Error :functionIsTypeImplies, 
universeEquality, 
pointwiseFunctionality, 
pertypeElimination, 
Error :productIsType, 
Error :equalityIsType4, 
equalityTransitivity, 
equalitySymmetry
Latex:
\mforall{}[P:\mBbbP{}].  (\mneg{}\00D9(P)  \mLeftarrow{}{}\mRightarrow{}  \mneg{}P)
Date html generated:
2019_06_20-PM-00_32_37
Last ObjectModification:
2018_10_06-PM-04_17_45
Theory : quot_1
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