Nuprl Lemma : left-convex2

g:EuclideanPlane. ∀a,b,x,y:Point.  (x leftof ab  (a_x_y ∨ (a_y_x ∧ y ≠ a))  leftof ab)


Proof




Definitions occuring in Statement :  euclidean-plane: EuclideanPlane geo-left: leftof bc geo-between: a_b_c geo-sep: a ≠ b geo-point: Point all: x:A. B[x] implies:  Q or: P ∨ Q and: P ∧ Q
Definitions unfolded in proof :  and: P ∧ Q uimplies: supposing a guard: {T} subtype_rel: A ⊆B uall: [x:A]. B[x] prop: member: t ∈ T implies:  Q all: x:A. B[x] or: P ∨ Q geo-lsep: bc subtract: m cons: [a b] select: L[n] true: True squash: T less_than: a < b not: ¬A false: False less_than': less_than'(a;b) le: A ≤ B lelt: i ≤ j < k int_seg: {i..j-} top: Top l_all: (∀x∈L.P[x]) geo-colinear-set: geo-colinear-set(e; L) cand: c∧ B
Lemmas referenced :  geo-point_wf geo-left_wf geo-sep_wf geo-primitives_wf euclidean-plane-structure_wf euclidean-plane_wf subtype_rel_transitivity euclidean-plane-subtype euclidean-plane-structure-subtype geo-between_wf or_wf left-symmetry lelt_wf false_wf length_of_nil_lemma length_of_cons_lemma geo-between-implies-colinear geo-colinear-is-colinear-set left-implies-sep geo-between-sep geo-sep-sym colinear-lsep lsep-symmetry not-left-and-right left-convex
Rules used in proof :  because_Cache productEquality sqequalRule independent_isectElimination instantiate hypothesis applyEquality hypothesisEquality thin isectElimination sqequalHypSubstitution extract_by_obid introduction cut lambdaFormation sqequalReflexivity computationStep sqequalTransitivity sqequalSubstitution independent_functionElimination dependent_functionElimination inlFormation unionElimination baseClosed imageMemberEquality independent_pairFormation natural_numberEquality dependent_set_memberEquality voidEquality voidElimination isect_memberEquality productElimination inrFormation

Latex:
\mforall{}g:EuclideanPlane.  \mforall{}a,b,x,y:Point.    (x  leftof  ab  {}\mRightarrow{}  (a\_x\_y  \mvee{}  (a\_y\_x  \mwedge{}  y  \mneq{}  a))  {}\mRightarrow{}  y  leftof  ab)



Date html generated: 2017_10_02-PM-04_40_41
Last ObjectModification: 2017_08_08-PM-03_52_22

Theory : euclidean!plane!geometry


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