Nuprl Lemma : strict-fun-connected_transitivity3
∀[T:Type]. ∀f:T ⟶ T. (retraction(T;f) 
⇒ (∀x,y,z:T.  (y = f+(x) 
⇒ z is f*(y) 
⇒ z = f+(x))))
Proof
Definitions occuring in Statement : 
retraction: retraction(T;f)
, 
strict-fun-connected: y = f+(x)
, 
fun-connected: y is f*(x)
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
function: x:A ⟶ B[x]
, 
universe: Type
Definitions unfolded in proof : 
strict-fun-connected: y = f+(x)
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
, 
cand: A c∧ B
, 
member: t ∈ T
, 
guard: {T}
, 
prop: ℙ
, 
not: ¬A
, 
false: False
, 
uimplies: b supposing a
Lemmas referenced : 
fun-connected_transitivity, 
fun-connected_wf, 
not_wf, 
equal_wf, 
retraction_wf, 
fun-connected_antisymmetry
Rules used in proof : 
sqequalSubstitution, 
sqequalRule, 
sqequalReflexivity, 
sqequalTransitivity, 
computationStep, 
isect_memberFormation, 
lambdaFormation, 
sqequalHypSubstitution, 
productElimination, 
thin, 
cut, 
independent_pairFormation, 
hypothesis, 
introduction, 
extract_by_obid, 
isectElimination, 
hypothesisEquality, 
dependent_functionElimination, 
independent_functionElimination, 
cumulativity, 
functionExtensionality, 
applyEquality, 
productEquality, 
functionEquality, 
universeEquality, 
equalitySymmetry, 
hyp_replacement, 
Error :applyLambdaEquality, 
voidElimination, 
independent_isectElimination
Latex:
\mforall{}[T:Type].  \mforall{}f:T  {}\mrightarrow{}  T.  (retraction(T;f)  {}\mRightarrow{}  (\mforall{}x,y,z:T.    (y  =  f+(x)  {}\mRightarrow{}  z  is  f*(y)  {}\mRightarrow{}  z  =  f+(x))))
Date html generated:
2016_10_25-AM-11_04_23
Last ObjectModification:
2016_07_12-AM-07_12_28
Theory : general
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