Nuprl Lemma : geo-be-end-eq
∀e:BasicGeometry. ∀a,b,c:Point.  (a_b_c ⇒ ab ≅ ac ⇒ b ≡ c)
Proof
Definitions occuring in Statement : 
basic-geometry: BasicGeometry, 
geo-eq: a ≡ b, 
geo-congruent: ab ≅ cd, 
geo-between: a_b_c, 
geo-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
member: t ∈ T, 
uall: ∀[x:A]. B[x], 
subtype_rel: A ⊆r B, 
guard: {T}, 
uimplies: b supposing a, 
prop: ℙ, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
squash: ↓T, 
basic-geometry: BasicGeometry, 
euclidean-plane: EuclideanPlane, 
true: True, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
geo-zero-length: 0
Lemmas referenced : 
geo-congruent_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
basic-geometry-subtype, 
subtype_rel_transitivity, 
basic-geometry_wf, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-between_wf, 
geo-point_wf, 
geo-add-length-between, 
geo-congruent-iff-length, 
equal_wf, 
squash_wf, 
true_wf, 
istype-universe, 
geo-length-type_wf, 
geo-add-length_wf, 
geo-length_wf, 
geo-mk-seg_wf, 
subtype_rel_self, 
iff_weakening_equal, 
geo-add-length-zero, 
geo-add-length-cancel-left, 
geo-zero-length_wf, 
geo-length-null-segment, 
geo-congruence-identity-sym
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
universeIsType, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
applyEquality, 
hypothesis, 
instantiate, 
independent_isectElimination, 
sqequalRule, 
because_Cache, 
inhabitedIsType, 
dependent_functionElimination, 
productElimination, 
lambdaEquality_alt, 
imageElimination, 
equalityTransitivity, 
equalitySymmetry, 
universeEquality, 
setElimination, 
rename, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
independent_functionElimination
Latex:
\mforall{}e:BasicGeometry.  \mforall{}a,b,c:Point.    (a\_b\_c  {}\mRightarrow{}  ab  \mcong{}  ac  {}\mRightarrow{}  b  \mequiv{}  c)
Date html generated:
2019_10_16-PM-01_25_43
Last ObjectModification:
2018_12_15-PM-09_59_35
Theory : euclidean!plane!geometry
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