Nuprl Lemma : angle-bisector-unique
∀e:EuclideanPlane. ∀a,b,c,a',c',x,y:Point.
  (a # bc ⇒ out(b aa') ⇒ out(b cc') ⇒ a-x-c ⇒ a'-y-c' ⇒ abx ≅a cbx ⇒ a'by ≅a c'by ⇒ {out(b xy) ∧ abx ≅a a'by})
Proof
Definitions occuring in Statement : 
geo-out: out(p ab), 
geo-cong-angle: abc ≅a xyz, 
euclidean-plane: EuclideanPlane, 
geo-strict-between: a-b-c, 
geo-lsep: a # bc, 
geo-point: Point, 
guard: {T}, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
and: P ∧ Q
Definitions unfolded in proof : 
geo-out: out(p ab), 
geo-midpoint: a=m=b, 
iff: P ⇐⇒ Q, 
basic-geometry-: BasicGeometry-, 
uimplies: b supposing a, 
subtype_rel: A ⊆r B, 
prop: ℙ, 
uall: ∀[x:A]. B[x], 
euclidean-plane: EuclideanPlane, 
exists: ∃x:A. B[x], 
basic-geometry: BasicGeometry, 
cand: A c∧ B, 
and: P ∧ Q, 
guard: {T}, 
member: t ∈ T, 
implies: P ⇒ Q, 
all: ∀x:A. B[x]
Lemmas referenced : 
out-cong-angle, 
out-preserves-angle-cong_1, 
geo-out_transitivity, 
geo-cong-angle_functionality, 
geo-out_functionality, 
geo-strict-between_functionality, 
geo-midpoint_functionality, 
at-most-one-midpoint, 
geo-cong-angle-transitivity, 
geo-sas2, 
geo-congruent-right-comm, 
geo-cong-angle-symm2, 
euclidean-plane-axioms, 
geo-congruent-refl, 
geo-congruent-symmetry, 
geo-eq_weakening, 
geo-out_weakening, 
geo-between-symmetry, 
geo-strict-between-implies-between, 
geo-out-iff-between1, 
geo-strict-between-sep3, 
geo-point_wf, 
geo-lsep_wf, 
geo-out_wf, 
geo-primitives_wf, 
euclidean-plane-structure_wf, 
euclidean-plane_wf, 
subtype_rel_transitivity, 
euclidean-plane-subtype, 
euclidean-plane-structure-subtype, 
geo-strict-between_wf, 
geo-cong-angle_wf, 
geo-sep-O-X, 
lsep-implies-sep, 
geo-sep-sym, 
geo-X_wf, 
geo-O_wf, 
geo-proper-extend-exists, 
geo-out_inversion, 
lsep-all-sym, 
lsep-symmetry, 
out-preserves-lsep, 
geo-out-interior-point-exists
Rules used in proof : 
promote_hyp, 
productIsType, 
independent_pairFormation, 
dependent_pairFormation_alt, 
inhabitedIsType, 
independent_isectElimination, 
instantiate, 
applyEquality, 
isectElimination, 
universeIsType, 
rename, 
setElimination, 
sqequalRule, 
productElimination, 
hypothesis, 
because_Cache, 
independent_functionElimination, 
hypothesisEquality, 
thin, 
dependent_functionElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
introduction, 
cut, 
lambdaFormation_alt, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}a,b,c,a',c',x,y:Point.
    (a  \#  bc
    {}\mRightarrow{}  out(b  aa')
    {}\mRightarrow{}  out(b  cc')
    {}\mRightarrow{}  a-x-c
    {}\mRightarrow{}  a'-y-c'
    {}\mRightarrow{}  abx  \mcong{}\msuba{}  cbx
    {}\mRightarrow{}  a'by  \mcong{}\msuba{}  c'by
    {}\mRightarrow{}  \{out(b  xy)  \mwedge{}  abx  \mcong{}\msuba{}  a'by\})
Date html generated:
2019_10_29-AM-09_20_43
Last ObjectModification:
2019_10_18-PM-04_37_29
Theory : euclidean!plane!geometry
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