Nuprl Lemma : Euclid-Prop16-construction-lemma
∀g:EuclideanPlane. ∀a,b,c:Point.
  (a # bc ⇒ (∃x:{x:Point| b=x=c} . ∃y:{y:Point| a=x=y} . (abc ≅a ycb ∧ (b ≠ x ∧ x ≠ c) ∧ a ≠ x ∧ x ≠ y)))
Proof
Definitions occuring in Statement : 
geo-cong-angle: abc ≅a xyz, 
euclidean-plane: EuclideanPlane, 
geo-lsep: a # bc, 
geo-midpoint: a=m=b, 
geo-sep: a ≠ b, 
geo-point: Point, 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
implies: P ⇒ Q, 
and: P ∧ Q, 
set: {x:A| B[x]} 
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
member: t ∈ T, 
guard: {T}, 
and: P ∧ Q, 
uall: ∀[x:A]. B[x], 
subtype_rel: A ⊆r B, 
prop: ℙ, 
sq_exists: ∃x:A [B[x]], 
euclidean-plane: EuclideanPlane, 
sq_stable: SqStable(P), 
squash: ↓T, 
exists: ∃x:A. B[x], 
cand: A c∧ B, 
basic-geometry: BasicGeometry, 
uimplies: b supposing a, 
geo-midpoint: a=m=b, 
geo-colinear-set: geo-colinear-set(e; L), 
l_all: (∀x∈L.P[x]), 
top: Top, 
int_seg: {i..j-}, 
lelt: i ≤ j < k, 
le: A ≤ B, 
less_than': less_than'(a;b), 
false: False, 
not: ¬A, 
less_than: a < b, 
true: True, 
select: L[n], 
cons: [a / b], 
subtract: n - m, 
basic-geometry-: BasicGeometry-, 
uiff: uiff(P;Q), 
geo-strict-between: a-b-c, 
geo-cong-angle: abc ≅a xyz
Lemmas referenced : 
Euclid-midpoint, 
lsep-implies-sep, 
geo-sep_wf, 
sq_stable__midpoint, 
geo-midpoint_wf, 
colinear-lsep, 
lsep-all-sym, 
geo-sep-sym, 
midpoint-sep, 
geo-colinear-permute, 
geo-colinear-is-colinear-set, 
geo-between-implies-colinear, 
length_of_cons_lemma, 
istype-void, 
length_of_nil_lemma, 
istype-false, 
istype-le, 
istype-less_than, 
geo-cong-angle_wf, 
geo-lsep_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
subtype_rel_transitivity, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-point_wf, 
colinear-implies-midpoint, 
geo-strict-between-sep1, 
geo-strict-between-implies-colinear, 
geo-congruent-iff-length, 
geo-length-flip, 
geo-strict-between-sep3, 
geo-proper-extend-exists, 
geo-strict-between-implies-between, 
geo-between-symmetry, 
euclidean-plane-axioms, 
geo-strict-between-sep2, 
geo-between-trivial, 
vertical-angles-congruent, 
geo-between_wf, 
geo-congruent_wf, 
geo-sas2, 
geo-between-out, 
geo-out_weakening, 
geo-eq_weakening, 
out-preserves-angle-cong_1
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
hypothesisEquality, 
because_Cache, 
independent_functionElimination, 
hypothesis, 
productElimination, 
dependent_set_memberEquality_alt, 
universeIsType, 
isectElimination, 
applyEquality, 
sqequalRule, 
setElimination, 
rename, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
dependent_pairFormation_alt, 
independent_isectElimination, 
isect_memberEquality_alt, 
voidElimination, 
natural_numberEquality, 
independent_pairFormation, 
productIsType, 
setIsType, 
instantiate, 
inhabitedIsType, 
equalityTransitivity, 
equalitySymmetry
Latex:
\mforall{}g:EuclideanPlane.  \mforall{}a,b,c:Point.
    (a  \#  bc
    {}\mRightarrow{}  (\mexists{}x:\{x:Point|  b=x=c\}  .  \mexists{}y:\{y:Point|  a=x=y\}  .  (abc  \mcong{}\msuba{}  ycb  \mwedge{}  (b  \mneq{}  x  \mwedge{}  x  \mneq{}  c)  \mwedge{}  a  \mneq{}  x  \mwedge{}  x  \mneq{}  y)))
Date html generated:
2019_10_16-PM-02_14_38
Last ObjectModification:
2018_12_03-PM-09_58_16
Theory : euclidean!plane!geometry
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