Nuprl Lemma : euclid-P3
∀e:EuclideanPlane. ∀A,B,C1,C2:Point.  ∃E:Point. (A_E_B ∧ AE=C1C2) supposing (¬(C1 = C2 ∈ Point)) ∧ |C1C2| < |AB|
Proof
Definitions occuring in Statement : 
eu-lt: p < q
, 
eu-length: |s|
, 
eu-mk-seg: ab
, 
euclidean-plane: EuclideanPlane
, 
eu-between-eq: a_b_c
, 
eu-congruent: ab=cd
, 
eu-point: Point
, 
uimplies: b supposing a
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
not: ¬A
, 
and: P ∧ Q
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
uimplies: b supposing a
, 
member: t ∈ T
, 
prop: ℙ
, 
and: P ∧ Q
, 
uall: ∀[x:A]. B[x]
, 
euclidean-plane: EuclideanPlane
, 
not: ¬A
, 
implies: P 
⇒ Q
, 
false: False
, 
uiff: uiff(P;Q)
, 
exists: ∃x:A. B[x]
, 
cand: A c∧ B
, 
stable: Stable{P}
, 
squash: ↓T
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
true: True
, 
subtype_rel: A ⊆r B
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
eu-lt: p < q
Lemmas referenced : 
not_wf, 
equal_wf, 
eu-point_wf, 
eu-lt_wf, 
eu-length_wf, 
eu-mk-seg_wf, 
euclidean-plane_wf, 
eu-extend-exists, 
eu-lt-null-segment, 
eu-congruent_wf, 
eu-between-eq_wf, 
eu-congruence-identity-sym, 
false_wf, 
eu-between-eq-same-side2, 
eu-between-eq-symmetry, 
stable__eu-between-eq, 
eu-add-length-between, 
eu-congruent-iff-length, 
eu-O_wf, 
eu-X_wf, 
eu-add-length_wf, 
squash_wf, 
true_wf, 
set_wf, 
iff_weakening_equal, 
eu-le-add1, 
eu-lt_transitivity
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
isect_memberFormation, 
productEquality, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
setElimination, 
rename, 
hypothesisEquality, 
hypothesis, 
because_Cache, 
dependent_functionElimination, 
productElimination, 
equalitySymmetry, 
hyp_replacement, 
Error :applyLambdaEquality, 
sqequalRule, 
independent_isectElimination, 
voidElimination, 
equalityTransitivity, 
equalityEquality, 
universeEquality, 
dependent_set_memberEquality, 
independent_functionElimination, 
dependent_pairFormation, 
independent_pairFormation, 
setEquality, 
applyEquality, 
lambdaEquality, 
imageElimination, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}A,B,C1,C2:Point.
    \mexists{}E:Point.  (A\_E\_B  \mwedge{}  AE=C1C2)  supposing  (\mneg{}(C1  =  C2))  \mwedge{}  |C1C2|  <  |AB|
Date html generated:
2016_10_26-AM-07_46_08
Last ObjectModification:
2016_08_29-PM-03_31_29
Theory : euclidean!geometry
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