Nuprl Lemma : eu-length-flip
∀e:EuclideanPlane. ∀[a,b:Point].  (|ab| = |ba| ∈ {p:Point| O_X_p} )
Proof
Definitions occuring in Statement : 
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, 
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], 
member: t ∈ T, 
eu-length: |s|, 
euclidean-plane: EuclideanPlane, 
and: P ∧ Q, 
prop: ℙ, 
uiff: uiff(P;Q), 
uimplies: b supposing a, 
subtype_rel: A ⊆r B
Lemmas referenced : 
eu-extend-property, 
eu-O_wf, 
eu-not-colinear-OXY, 
eu-X_wf, 
not_wf, 
equal_wf, 
eu-point_wf, 
eu-seg1_wf, 
eu-mk-seg_wf, 
eu-seg2_wf, 
eu-between-eq_wf, 
eu-seg-congruent-iff-length, 
eu-congruent-flip-seg
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
isect_memberFormation, 
introduction, 
cut, 
dependent_set_memberEquality, 
sqequalRule, 
lemma_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
because_Cache, 
isectElimination, 
setElimination, 
rename, 
hypothesisEquality, 
hypothesis, 
productElimination, 
isect_memberEquality, 
axiomEquality, 
independent_isectElimination, 
applyEquality
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}[a,b:Point].    (|ab|  =  |ba|)
Date html generated:
2016_05_18-AM-06_37_41
Last ObjectModification:
2015_12_28-AM-09_24_39
Theory : euclidean!geometry
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