Nuprl Lemma : inl_equal
∀[A,B:Type]. ∀[x,y:A].  uiff((inl x) = (inl y) ∈ (A + B);x = y ∈ A)
Proof
Definitions occuring in Statement : 
uiff: uiff(P;Q), 
uall: ∀[x:A]. B[x], 
inl: inl x, 
union: left + right, 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
uimplies: b supposing a, 
outl: outl(x), 
prop: ℙ, 
isl: isl(x), 
assert: ↑b, 
ifthenelse: if b then t else f fi , 
btrue: tt, 
true: True
Lemmas referenced : 
and_wf, 
equal_wf, 
outl_wf, 
assert_wf, 
isl_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
independent_pairFormation, 
sqequalRule, 
hypothesisEquality, 
equalitySymmetry, 
dependent_set_memberEquality, 
hypothesis, 
equalityTransitivity, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
unionEquality, 
applyEquality, 
lambdaEquality, 
setElimination, 
rename, 
productElimination, 
independent_isectElimination, 
promote_hyp, 
hyp_replacement, 
Error :applyLambdaEquality, 
natural_numberEquality, 
setEquality, 
cumulativity, 
inlEquality, 
independent_pairEquality, 
isect_memberEquality, 
axiomEquality, 
because_Cache, 
universeEquality
Latex:
\mforall{}[A,B:Type].  \mforall{}[x,y:A].    uiff((inl  x)  =  (inl  y);x  =  y)
 Date html generated: 
2016_10_25-AM-10_50_45
 Last ObjectModification: 
2016_07_12-AM-06_59_36
Theory : general
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