Nuprl Lemma : eu-add-length-between-iff
∀e:EuclideanPlane. ∀[a,b,c:Point].  uiff(a_b_c;|ac| = |ab| + |bc| ∈ {p:Point| O_X_p} )
Proof
Definitions occuring in Statement : 
eu-add-length: p + q, 
eu-length: |s|, 
eu-mk-seg: ab, 
euclidean-plane: EuclideanPlane, 
eu-between-eq: a_b_c, 
eu-X: X, 
eu-O: O, 
eu-point: Point, 
uiff: uiff(P;Q), 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x], 
set: {x:A| B[x]} , 
equal: s = t ∈ T
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
uall: ∀[x:A]. B[x], 
uiff: uiff(P;Q), 
and: P ∧ Q, 
uimplies: b supposing a, 
member: t ∈ T, 
prop: ℙ, 
euclidean-plane: EuclideanPlane, 
stable: Stable{P}, 
not: ¬A, 
implies: P ⇒ Q, 
false: False, 
exists: ∃x:A. B[x], 
squash: ↓T, 
true: True, 
subtype_rel: A ⊆r B, 
guard: {T}, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
cand: A c∧ B
Lemmas referenced : 
eu-between-eq_wf, 
equal_wf, 
eu-point_wf, 
eu-O_wf, 
eu-X_wf, 
eu-length_wf, 
eu-mk-seg_wf, 
eu-add-length_wf, 
euclidean-plane_wf, 
eu-add-length-between, 
stable__eu-between-eq, 
eu-between-eq-trivial-left, 
not_wf, 
eu-le-add1, 
eu-le_wf, 
eu-le-null-segment, 
eu-congruence-identity, 
eu-congruent-iff-length, 
eu-extend-exists, 
eu-congruent_wf, 
eu-congruence-identity-sym, 
false_wf, 
squash_wf, 
true_wf, 
euclidean-structure_wf, 
iff_weakening_equal, 
eu-between-eq-trivial-right, 
set_wf, 
eu-add-length-zero2, 
eu-add-length-assoc, 
eu-add-length-cancel-left, 
eu-between-eq-same-side2, 
eu-between-eq-symmetry, 
eu-congruent-between-implies-equal, 
and_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
isect_memberFormation, 
independent_pairFormation, 
cut, 
hypothesis, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
setElimination, 
rename, 
hypothesisEquality, 
axiomEquality, 
setEquality, 
because_Cache, 
dependent_functionElimination, 
independent_isectElimination, 
independent_functionElimination, 
hyp_replacement, 
equalitySymmetry, 
Error :applyLambdaEquality, 
sqequalRule, 
voidElimination, 
dependent_set_memberEquality, 
productElimination, 
equalityTransitivity, 
equalityEquality, 
universeEquality, 
applyEquality, 
lambdaEquality, 
imageElimination, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}[a,b,c:Point].    uiff(a\_b\_c;|ac|  =  |ab|  +  |bc|)
Date html generated:
2016_10_26-AM-07_44_23
Last ObjectModification:
2016_07_12-AM-08_12_02
Theory : euclidean!geometry
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