Nuprl Lemma : lsep-implies-sep-or-lsep
∀e:EuclideanPlane. ∀a,b,c,x:Point.  (a # bc 
⇒ (c ≠ x ∨ x # ab))
Proof
Definitions occuring in Statement : 
euclidean-plane: EuclideanPlane
, 
geo-lsep: a # bc
, 
geo-sep: a ≠ b
, 
geo-point: Point
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
or: P ∨ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
member: t ∈ T
, 
oriented-plane: OrientedPlane
, 
geo-colinear-set: geo-colinear-set(e; L)
, 
l_all: (∀x∈L.P[x])
, 
top: Top
, 
int_seg: {i..j-}
, 
lelt: i ≤ j < k
, 
and: P ∧ Q
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
uall: ∀[x:A]. B[x]
, 
uimplies: b supposing a
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
prop: ℙ
, 
false: False
, 
select: L[n]
, 
cons: [a / b]
, 
subtract: n - m
, 
subtype_rel: A ⊆r B
, 
guard: {T}
, 
sq_exists: ∃x:A [B[x]]
, 
euclidean-plane: EuclideanPlane
, 
sq_stable: SqStable(P)
, 
squash: ↓T
, 
basic-geometry: BasicGeometry
, 
geo-equilateral: EQΔ(a;b;c)
, 
geo-midpoint: a=m=b
, 
uiff: uiff(P;Q)
, 
cand: A c∧ B
, 
l_member: (x ∈ l)
, 
nat: ℕ
, 
le: A ≤ B
, 
less_than': less_than'(a;b)
, 
less_than: a < b
, 
true: True
, 
ge: i ≥ j 
, 
append: as @ bs
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
so_apply: x[s1;s2;s3]
, 
iff: P 
⇐⇒ Q
Lemmas referenced : 
lsep-colinear-sep1, 
geo-colinear-is-colinear-set, 
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, 
geo-colinear_wf, 
lsep-symmetry, 
euclidean-plane-axioms, 
colinear-equidistant-points-exist, 
geo-sep-sym, 
lsep-implies-sep, 
geo-sep_wf, 
geo-lsep_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
subtype_rel_transitivity, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-point_wf, 
Euclid-midpoint, 
sq_stable__midpoint, 
midpoint-sep, 
Euclid-Prop1, 
upper-dimension-axiom, 
geo-congruent-iff-length, 
geo-length-flip, 
colinear-lsep-cycle, 
lsep-all-sym, 
geo-between-implies-colinear, 
geo-colinear-permute, 
geo-colinear-append, 
cons_wf, 
nil_wf, 
length_wf, 
select_wf, 
nat_properties, 
intformand_wf, 
itermVar_wf, 
int_formula_prop_and_lemma, 
int_term_value_var_lemma, 
l_member_wf, 
list_ind_cons_lemma, 
list_ind_nil_lemma, 
geo-sep-or, 
colinear-lsep, 
colinear-lsep', 
lsep-symmetry2, 
geo-colinear-cycle, 
or_comm
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
sqequalRule, 
hypothesisEquality, 
independent_functionElimination, 
hypothesis, 
isect_memberEquality_alt, 
voidElimination, 
dependent_set_memberEquality_alt, 
natural_numberEquality, 
independent_pairFormation, 
unionElimination, 
isectElimination, 
independent_isectElimination, 
approximateComputation, 
dependent_pairFormation_alt, 
lambdaEquality_alt, 
universeIsType, 
productIsType, 
applyEquality, 
because_Cache, 
productElimination, 
instantiate, 
inhabitedIsType, 
setElimination, 
rename, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
equalityTransitivity, 
equalitySymmetry, 
equalityIstype, 
int_eqEquality, 
inlFormation_alt, 
inrFormation_alt
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}a,b,c,x:Point.    (a  \#  bc  {}\mRightarrow{}  (c  \mneq{}  x  \mvee{}  x  \#  ab))
Date html generated:
2019_10_16-PM-02_33_30
Last ObjectModification:
2019_07_23-PM-10_01_49
Theory : euclidean!plane!geometry
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