Nuprl Lemma : geo-length-flip-eq
∀e:BasicGeometry. ∀[a,b:Point].  |ab| ≡ |ba|
Proof
Definitions occuring in Statement : 
geo-length: |s|, 
geo-mk-seg: ab, 
basic-geometry: BasicGeometry, 
geo-eq: a ≡ b, 
geo-point: Point, 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x]
Definitions unfolded in proof : 
guard: {T}, 
subtype_rel: A ⊆r B, 
false: False, 
implies: P ⇒ Q, 
not: ¬A, 
geo-eq: a ≡ b, 
uimplies: b supposing a, 
and: P ∧ Q, 
uiff: uiff(P;Q), 
euclidean-plane: EuclideanPlane, 
basic-geometry: BasicGeometry, 
member: t ∈ T, 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x]
Lemmas referenced : 
geo-primitives_wf, 
euclidean-plane-structure_wf, 
euclidean-plane_wf, 
basic-geometry_wf, 
subtype_rel_transitivity, 
basic-geometry-subtype, 
euclidean-plane-subtype, 
euclidean-plane-structure-subtype, 
geo-point_wf, 
geo-congruent-flip-seg, 
geo-mk-seg_wf, 
geo-seg-congruent-iff-length
Rules used in proof : 
instantiate, 
applyEquality, 
universeIsType, 
isectIsTypeImplies, 
voidElimination, 
isect_memberEquality_alt, 
inhabitedIsType, 
functionIsTypeImplies, 
lambdaEquality_alt, 
sqequalRule, 
independent_isectElimination, 
productElimination, 
hypothesisEquality, 
hypothesis, 
rename, 
setElimination, 
isectElimination, 
because_Cache, 
thin, 
dependent_functionElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
cut, 
introduction, 
isect_memberFormation_alt, 
lambdaFormation_alt, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}e:BasicGeometry.  \mforall{}[a,b:Point].    |ab|  \mequiv{}  |ba|
Date html generated:
2019_10_29-AM-09_13_36
Last ObjectModification:
2019_10_18-PM-03_17_53
Theory : euclidean!plane!geometry
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