Nuprl Lemma : geo-congruent-mid-exists
∀e:HeytingGeometry. ∀A,B,C:Point.  (A # BC 
⇒ CA ≅ CB 
⇒ (∃x:Point. A=x=B))
Proof
Definitions occuring in Statement : 
geo-triangle: a # bc
, 
heyting-geometry: HeytingGeometry
, 
geo-midpoint: a=m=b
, 
geo-congruent: ab ≅ cd
, 
geo-point: Point
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
implies: P 
⇒ Q
Definitions unfolded in proof : 
heyting-geometry: Error :heyting-geometry, 
prop: ℙ
, 
uimplies: b supposing a
, 
uiff: uiff(P;Q)
, 
uall: ∀[x:A]. B[x]
, 
subtype_rel: A ⊆r B
, 
cand: A c∧ B
, 
and: P ∧ Q
, 
guard: {T}
, 
member: t ∈ T
, 
implies: P 
⇒ Q
, 
all: ∀x:A. B[x]
Lemmas referenced : 
geo-point_wf, 
Error :geo-triangle_wf, 
Error :basic-geo-primitives_wf, 
Error :basic-geo-structure_wf, 
basic-geometry_wf, 
Error :heyting-geometry_wf, 
subtype_rel_transitivity, 
basic-geometry-subtype, 
geo-congruent_wf, 
geo-length-flip, 
heyting-geometry-subtype, 
geo-congruent-iff-length, 
geo-triangle-symmetry, 
isosceles-mid-exists
Rules used in proof : 
rename, 
setElimination, 
instantiate, 
equalitySymmetry, 
equalityTransitivity, 
independent_isectElimination, 
isectElimination, 
sqequalRule, 
applyEquality, 
productElimination, 
hypothesis, 
because_Cache, 
independent_functionElimination, 
hypothesisEquality, 
thin, 
dependent_functionElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
introduction, 
cut, 
lambdaFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}e:HeytingGeometry.  \mforall{}A,B,C:Point.    (A  \#  BC  {}\mRightarrow{}  CA  \00D0  CB  {}\mRightarrow{}  (\mexists{}x:Point.  A=x=B))
Date html generated:
2017_10_02-PM-07_09_30
Last ObjectModification:
2017_08_08-PM-00_41_08
Theory : euclidean!plane!geometry
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