Nuprl Lemma : geo-lt-angle-in-half-plane-implies-left
∀e:EuclideanPlane. ∀w,x,y,z:Point.  (xyz < wyz 
⇒ w leftof yz 
⇒ x leftof yz 
⇒ w leftof yx)
Proof
Definitions occuring in Statement : 
geo-lt-angle: abc < xyz
, 
euclidean-plane: EuclideanPlane
, 
geo-left: a leftof bc
, 
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
, 
uall: ∀[x:A]. B[x]
, 
subtype_rel: A ⊆r B
, 
guard: {T}
, 
uimplies: b supposing a
, 
prop: ℙ
, 
and: P ∧ Q
, 
cand: A c∧ B
, 
geo-lt-angle: abc < xyz
, 
exists: ∃x:A. B[x]
, 
geo-lsep: a # bc
, 
or: P ∨ Q
, 
geo-out: out(p ab)
, 
basic-geometry: BasicGeometry
, 
geo-colinear-set: geo-colinear-set(e; L)
, 
l_all: (∀x∈L.P[x])
, 
top: Top
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
decidable: Dec(P)
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
false: False
, 
select: L[n]
, 
cons: [a / b]
, 
subtract: n - m
, 
oriented-plane: OrientedPlane
Lemmas referenced : 
geo-left_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
subtype_rel_transitivity, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-lt-angle_wf, 
geo-point_wf, 
lsep-all-sym2, 
geo-lt-angle-symm, 
lsep-all-sym, 
colinear-lsep, 
geo-sep-sym, 
geo-colinear-is-colinear-set, 
geo-out-colinear, 
length_of_cons_lemma, 
istype-void, 
length_of_nil_lemma, 
decidable__le, 
full-omega-unsat, 
intformnot_wf, 
intformle_wf, 
itermConstant_wf, 
istype-int, 
int_formula_prop_not_lemma, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_formula_prop_wf, 
decidable__lt, 
intformless_wf, 
int_formula_prop_less_lemma, 
istype-le, 
istype-less_than, 
colinear-lsep2, 
geo-between-implies-colinear, 
left-implies-sep, 
interior-angles-unique2, 
lsep-symmetry, 
geo-out_weakening, 
geo-eq_weakening, 
out-preserves-lsep, 
cong-angle-preserves-lsep_strong, 
geo-between-sep, 
lsep-implies-sep, 
geo-between_wf, 
geo-cong-angle-symm2, 
out-preserves-angle-cong_1, 
geo-left-out, 
geo-left-out-2, 
geo-left-out-3, 
geo-out_inversion, 
geo-lt-angle-symm2, 
geo-cong-angle-symmetry, 
geo-lt-angle-left, 
lt-angle-irrefl
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
universeIsType, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
applyEquality, 
hypothesis, 
instantiate, 
independent_isectElimination, 
sqequalRule, 
because_Cache, 
dependent_functionElimination, 
inhabitedIsType, 
independent_functionElimination, 
productElimination, 
inlFormation_alt, 
isect_memberEquality_alt, 
voidElimination, 
dependent_set_memberEquality_alt, 
natural_numberEquality, 
independent_pairFormation, 
unionElimination, 
approximateComputation, 
dependent_pairFormation_alt, 
lambdaEquality_alt, 
productIsType, 
functionIsType
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}w,x,y,z:Point.    (xyz  <  wyz  {}\mRightarrow{}  w  leftof  yz  {}\mRightarrow{}  x  leftof  yz  {}\mRightarrow{}  w  leftof  yx)
Date html generated:
2019_10_16-PM-02_28_56
Last ObjectModification:
2019_09_24-PM-03_28_21
Theory : euclidean!plane!geometry
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