Nuprl Lemma : colinear-lsep-cycle
∀g:EuclideanPlane. ∀a,b,c,y:Point.  (a # bc ⇒ y ≠ b ⇒ Colinear(a;b;y) ⇒ y # bc)
Proof
Definitions occuring in Statement : 
euclidean-plane: EuclideanPlane, 
geo-lsep: a # bc, 
geo-colinear: Colinear(a;b;c), 
geo-sep: a ≠ b, 
geo-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q
Definitions unfolded in proof : 
uimplies: b supposing a, 
guard: {T}, 
subtype_rel: A ⊆r B, 
subtract: n - m, 
cons: [a / b], 
select: L[n], 
uall: ∀[x:A]. B[x], 
true: True, 
squash: ↓T, 
less_than: a < b, 
prop: ℙ, 
not: ¬A, 
false: False, 
less_than': less_than'(a;b), 
le: A ≤ B, 
and: P ∧ Q, 
lelt: i ≤ j < k, 
int_seg: {i..j-}, 
top: Top, 
l_all: (∀x∈L.P[x]), 
geo-colinear-set: geo-colinear-set(e; L), 
implies: P ⇒ Q, 
member: t ∈ T, 
all: ∀x:A. B[x]
Lemmas referenced : 
geo-point_wf, 
geo-primitives_wf, 
euclidean-plane-structure_wf, 
euclidean-plane_wf, 
subtype_rel_transitivity, 
euclidean-plane-subtype, 
euclidean-plane-structure-subtype, 
geo-lsep_wf, 
geo-sep_wf, 
geo-colinear_wf, 
lelt_wf, 
false_wf, 
length_of_nil_lemma, 
length_of_cons_lemma, 
geo-colinear-is-colinear-set, 
colinear-lsep
Rules used in proof : 
independent_isectElimination, 
instantiate, 
applyEquality, 
because_Cache, 
isectElimination, 
baseClosed, 
imageMemberEquality, 
independent_pairFormation, 
natural_numberEquality, 
dependent_set_memberEquality, 
voidEquality, 
voidElimination, 
isect_memberEquality, 
sqequalRule, 
independent_functionElimination, 
hypothesisEquality, 
thin, 
dependent_functionElimination, 
sqequalHypSubstitution, 
hypothesis, 
lambdaFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution, 
extract_by_obid, 
introduction, 
cut
Latex:
\mforall{}g:EuclideanPlane.  \mforall{}a,b,c,y:Point.    (a  \#  bc  {}\mRightarrow{}  y  \mneq{}  b  {}\mRightarrow{}  Colinear(a;b;y)  {}\mRightarrow{}  y  \#  bc)
Date html generated:
2017_10_02-PM-04_47_14
Last ObjectModification:
2017_08_07-PM-00_02_14
Theory : euclidean!plane!geometry
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