Nuprl Lemma : dist-lemma-lt2
∀g:EuclideanPlane. ∀a,b,c,d,e,f:Point.  (|ef| < |ab| + |cd| ⇒ D(a;b;c;d;e;f))
Proof
Definitions occuring in Statement : 
dist: D(a;b;c;d;e;f), 
geo-lt: p < q, 
geo-add-length: p + q, 
geo-length: |s|, 
geo-mk-seg: ab, 
euclidean-plane: EuclideanPlane, 
geo-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
dist: D(a;b;c;d;e;f), 
exists: ∃x:A. B[x], 
member: t ∈ T, 
euclidean-plane: EuclideanPlane, 
uall: ∀[x:A]. B[x], 
basic-geometry: BasicGeometry, 
subtype_rel: A ⊆r B, 
and: P ∧ Q, 
cand: A c∧ B, 
guard: {T}, 
uimplies: b supposing a, 
prop: ℙ, 
iff: P ⇐⇒ Q
Lemmas referenced : 
geo-X_wf, 
geo-length_wf1, 
geo-mk-seg_wf, 
geo-add-length_wf1, 
geo-add-length-property1, 
geo-length-property, 
geo-add-length-property2, 
geo-between_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
subtype_rel_transitivity, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-congruent_wf, 
geo-sep_wf, 
geo-lt_wf, 
geo-length_wf, 
geo-add-length_wf, 
geo-point_wf, 
geo-lt-iff-strict-between-points, 
geo-sep-sym, 
geo-le-iff-between-points
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
dependent_pairFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
setElimination, 
rename, 
because_Cache, 
hypothesis, 
isectElimination, 
sqequalRule, 
hypothesisEquality, 
applyEquality, 
lambdaEquality_alt, 
inhabitedIsType, 
equalityTransitivity, 
equalitySymmetry, 
independent_pairFormation, 
productIsType, 
universeIsType, 
instantiate, 
independent_isectElimination, 
setIsType, 
productElimination, 
independent_functionElimination, 
dependent_set_memberEquality_alt
Latex:
\mforall{}g:EuclideanPlane.  \mforall{}a,b,c,d,e,f:Point.    (|ef|  <  |ab|  +  |cd|  {}\mRightarrow{}  D(a;b;c;d;e;f))
Date html generated:
2019_10_16-PM-02_50_44
Last ObjectModification:
2018_10_03-AM-11_23_23
Theory : euclidean!plane!geometry
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