Nuprl Lemma : test-colinear-sets
∀e:EuclideanPlane. ∀A,B,C,X,Y,Z,W,U,V:Point.
  (Colinear(A;B;X) ⇒ A_B_C ⇒ Y_C_A ⇒ (¬(Y = C ∈ Point)) ⇒ Colinear(C;Y;X))
Proof
Definitions occuring in Statement : 
euclidean-plane: EuclideanPlane, 
eu-between-eq: a_b_c, 
eu-colinear: Colinear(a;b;c), 
eu-point: Point, 
all: ∀x:A. B[x], 
not: ¬A, 
implies: P ⇒ Q, 
equal: s = t ∈ T
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
not: ¬A, 
false: False, 
member: t ∈ T, 
prop: ℙ, 
uall: ∀[x:A]. B[x], 
euclidean-plane: EuclideanPlane, 
exists: ∃x:A. B[x], 
and: P ∧ Q, 
cand: A c∧ B, 
uimplies: b supposing a, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
guard: {T}, 
or: P ∨ Q, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
append: as @ bs, 
so_lambda: so_lambda(x,y,z.t[x; y; z]), 
top: Top, 
so_apply: x[s1;s2;s3], 
eu-colinear-set: eu-colinear-set(e;L), 
l_all: (∀x∈L.P[x]), 
int_seg: {i..j-}, 
lelt: i ≤ j < k, 
le: A ≤ B, 
less_than': less_than'(a;b), 
less_than: a < b, 
squash: ↓T, 
true: True, 
select: L[n], 
cons: [a / b], 
subtract: n - m
Lemmas referenced : 
equal_wf, 
eu-point_wf, 
eu-colinear-append, 
cons_wf, 
nil_wf, 
eu-between-eq_wf, 
eu-between-eq-same, 
eu-colinear-def, 
cons_member, 
l_member_wf, 
not_wf, 
exists_wf, 
eu-colinear-is-colinear-set, 
eu-between-eq-implies-colinear, 
list_ind_cons_lemma, 
list_ind_nil_lemma, 
length_of_cons_lemma, 
length_of_nil_lemma, 
false_wf, 
lelt_wf, 
eu-colinear_wf, 
euclidean-plane_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
cut, 
hypothesis, 
sqequalHypSubstitution, 
independent_functionElimination, 
thin, 
equalitySymmetry, 
voidElimination, 
introduction, 
extract_by_obid, 
isectElimination, 
setElimination, 
rename, 
hypothesisEquality, 
dependent_functionElimination, 
because_Cache, 
dependent_pairFormation, 
hyp_replacement, 
Error :applyLambdaEquality, 
sqequalRule, 
independent_isectElimination, 
productElimination, 
independent_pairFormation, 
inrFormation, 
inlFormation, 
productEquality, 
lambdaEquality, 
isect_memberEquality, 
voidEquality, 
dependent_set_memberEquality, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}A,B,C,X,Y,Z,W,U,V:Point.
    (Colinear(A;B;X)  {}\mRightarrow{}  A\_B\_C  {}\mRightarrow{}  Y\_C\_A  {}\mRightarrow{}  (\mneg{}(Y  =  C))  {}\mRightarrow{}  Colinear(C;Y;X))
Date html generated:
2016_10_26-AM-07_44_10
Last ObjectModification:
2016_07_12-AM-08_11_36
Theory : euclidean!geometry
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