Nuprl Lemma : left-between-implies-right1
∀g:OrientedPlane. ∀a,b,x,y:Point.  (x leftof ab ⇒ x_b_y ⇒ y ≠ b ⇒ y leftof ba)
Proof
Definitions occuring in Statement : 
oriented-plane: OrientedPlane, 
geo-left: a leftof bc, 
geo-between: a_b_c, 
geo-sep: a ≠ b, 
geo-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
member: t ∈ T, 
oriented-plane: OrientedPlane, 
guard: {T}, 
and: P ∧ Q, 
cand: A c∧ B, 
uall: ∀[x:A]. B[x], 
uimplies: b supposing a, 
geo-colinear-set: geo-colinear-set(e; L), 
l_all: (∀x∈L.P[x]), 
top: Top, 
int_seg: {i..j-}, 
lelt: i ≤ j < k, 
le: A ≤ B, 
less_than': less_than'(a;b), 
false: False, 
not: ¬A, 
prop: ℙ, 
less_than: a < b, 
squash: ↓T, 
true: True, 
select: L[n], 
cons: [a / b], 
subtract: n - m, 
subtype_rel: A ⊆r B, 
iff: P ⇐⇒ Q, 
exists: ∃x:A. B[x]
Lemmas referenced : 
lsep-opposite-iff, 
lsep-all-sym2, 
colinear-lsep-cycle, 
geo-colinear-is-colinear-set, 
geo-between-implies-colinear, 
length_of_cons_lemma, 
length_of_nil_lemma, 
false_wf, 
lelt_wf, 
lsep-all-sym, 
geo-sep_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
oriented-plane-subtype, 
subtype_rel_transitivity, 
oriented-plane_wf, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-between_wf, 
geo-left_wf, 
geo-point_wf, 
geo-colinear-same, 
euclidean-plane-subtype-basic, 
basic-geometry_wf, 
geo-colinear_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
hypothesisEquality, 
independent_functionElimination, 
because_Cache, 
hypothesis, 
productElimination, 
isectElimination, 
independent_isectElimination, 
sqequalRule, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
dependent_set_memberEquality, 
natural_numberEquality, 
independent_pairFormation, 
imageMemberEquality, 
baseClosed, 
applyEquality, 
instantiate, 
dependent_pairFormation, 
productEquality
Latex:
\mforall{}g:OrientedPlane.  \mforall{}a,b,x,y:Point.    (x  leftof  ab  {}\mRightarrow{}  x\_b\_y  {}\mRightarrow{}  y  \mneq{}  b  {}\mRightarrow{}  y  leftof  ba)
Date html generated:
2018_05_22-AM-11_54_44
Last ObjectModification:
2018_04_17-PM-05_54_20
Theory : euclidean!plane!geometry
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