Nuprl Lemma : not-lt-zero-angle
∀e:EuclideanPlane. ∀a,b,c,x,y,z:Point.  (abc < xyz ⇒ (y_z_x ∨ y_x_z) ⇒ False)
Proof
Definitions occuring in Statement : 
geo-lt-angle: abc < xyz, 
euclidean-plane: EuclideanPlane, 
geo-between: a_b_c, 
geo-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
or: P ∨ Q, 
false: False
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
false: False, 
geo-lt-angle: abc < xyz, 
and: P ∧ Q, 
exists: ∃x:A. B[x], 
or: P ∨ Q, 
member: t ∈ T, 
basic-geometry: BasicGeometry, 
geo-out: out(p ab), 
not: ¬A, 
uall: ∀[x:A]. B[x], 
subtype_rel: A ⊆r B, 
guard: {T}, 
uimplies: b supposing a, 
prop: ℙ
Lemmas referenced : 
geo-out_inversion, 
geo-between-out, 
euclidean-plane-axioms, 
geo-sep-sym, 
geo-between_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
subtype_rel_transitivity, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-lt-angle_wf, 
geo-point_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
sqequalHypSubstitution, 
productElimination, 
thin, 
unionElimination, 
introduction, 
extract_by_obid, 
dependent_functionElimination, 
sqequalRule, 
hypothesisEquality, 
independent_functionElimination, 
because_Cache, 
hypothesis, 
voidElimination, 
unionIsType, 
universeIsType, 
isectElimination, 
applyEquality, 
instantiate, 
independent_isectElimination, 
inhabitedIsType
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}a,b,c,x,y,z:Point.    (abc  <  xyz  {}\mRightarrow{}  (y\_z\_x  \mvee{}  y\_x\_z)  {}\mRightarrow{}  False)
Date html generated:
2019_10_16-PM-01_49_25
Last ObjectModification:
2019_09_27-PM-05_58_24
Theory : euclidean!plane!geometry
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