Nuprl Lemma : eu-segments-cross
∀e:EuclideanPlane. ∀p,b,q,a:Point.  ((∃c:Point. ((¬Colinear(a;b;c)) ∧ a-p-c ∧ b_q_c)) 
⇒ (∃x:Point. (p-x-b ∧ q-x-a)))
Proof
Definitions occuring in Statement : 
euclidean-plane: EuclideanPlane
, 
eu-between-eq: a_b_c
, 
eu-colinear: Colinear(a;b;c)
, 
eu-between: a-b-c
, 
eu-point: Point
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
not: ¬A
, 
implies: P 
⇒ Q
, 
and: P ∧ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
exists: ∃x:A. B[x]
, 
and: P ∧ Q
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
, 
euclidean-plane: EuclideanPlane
, 
prop: ℙ
, 
cand: A c∧ B
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
Lemmas referenced : 
eu-inner-pasch-property, 
not_wf, 
eu-colinear_wf, 
eu-between_wf, 
eu-between-eq_wf, 
eu-inner-pasch_wf, 
and_wf, 
exists_wf, 
eu-point_wf, 
euclidean-plane_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
sqequalHypSubstitution, 
productElimination, 
thin, 
cut, 
lemma_by_obid, 
dependent_functionElimination, 
hypothesisEquality, 
isectElimination, 
dependent_set_memberEquality, 
because_Cache, 
hypothesis, 
setElimination, 
rename, 
dependent_pairFormation, 
independent_pairFormation, 
sqequalRule, 
lambdaEquality
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}p,b,q,a:Point.
    ((\mexists{}c:Point.  ((\mneg{}Colinear(a;b;c))  \mwedge{}  a-p-c  \mwedge{}  b\_q\_c))  {}\mRightarrow{}  (\mexists{}x:Point.  (p-x-b  \mwedge{}  q-x-a)))
Date html generated:
2016_05_18-AM-06_33_43
Last ObjectModification:
2015_12_28-AM-09_27_47
Theory : euclidean!geometry
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