Nuprl Lemma : geo-Aax4
∀g:EuclideanPlane. ∀a,b,c:Point. ∀l,m:Line.  (a ≠ b ⇒ (a I l ∧ b I l) ⇒ ((a I m ∧ c I m) ∧ c # l) ⇒ b # m)
Proof
Definitions occuring in Statement : 
geo-plsep: p # l, 
geo-incident: p I L, 
geo-line: Line, 
euclidean-plane: EuclideanPlane, 
geo-sep: a ≠ b, 
geo-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
and: P ∧ Q
Definitions unfolded in proof : 
so_apply: x[s1;s2;s3], 
so_lambda: so_lambda(x,y,z.t[x; y; z]), 
append: as @ bs, 
so_apply: x[s], 
so_lambda: λ2x.t[x], 
rev_implies: P ⇐ Q, 
iff: P ⇐⇒ Q, 
exists: ∃x:A. B[x], 
subtract: n - 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), 
geo-incident: p I L, 
cand: A c∧ B, 
oriented-plane: OrientedPlane, 
or: P ∨ Q, 
euclidean-plane: EuclideanPlane, 
uimplies: b supposing a, 
guard: {T}, 
subtype_rel: A ⊆r B, 
uall: ∀[x:A]. B[x], 
prop: ℙ, 
member: t ∈ T, 
pi2: snd(t), 
pi1: fst(t), 
geo-plsep: p # l, 
geo-line: Line, 
and: P ∧ Q, 
implies: P ⇒ Q, 
all: ∀x:A. B[x]
Lemmas referenced : 
geo-colinear_wf, 
top_wf, 
subtype_rel_product, 
pi1_wf_top, 
and_wf, 
colinear-lsep, 
geo-sep-sym, 
list_ind_nil_lemma, 
list_ind_cons_lemma, 
exists_wf, 
equal_wf, 
l_member_wf, 
cons_member, 
nil_wf, 
cons_wf, 
oriented-colinear-append, 
lelt_wf, 
false_wf, 
length_of_nil_lemma, 
length_of_cons_lemma, 
geo-colinear-is-colinear-set, 
geoline_wf, 
trivial-equal, 
lsep-all-sym, 
colinear-lsep', 
geo-sep-or, 
geo-point_wf, 
geo-line_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-plsep_wf, 
geoline-subtype1, 
geo-incident_wf
Rules used in proof : 
imageElimination, 
applyLambdaEquality, 
hyp_replacement, 
equalitySymmetry, 
equalityTransitivity, 
independent_pairEquality, 
lambdaEquality, 
inlFormation, 
inrFormation, 
dependent_pairFormation, 
baseClosed, 
imageMemberEquality, 
independent_pairFormation, 
natural_numberEquality, 
voidEquality, 
voidElimination, 
isect_memberEquality, 
dependent_pairEquality, 
independent_functionElimination, 
unionElimination, 
dependent_set_memberEquality, 
rename, 
setElimination, 
dependent_functionElimination, 
because_Cache, 
independent_isectElimination, 
instantiate, 
hypothesis, 
applyEquality, 
hypothesisEquality, 
isectElimination, 
extract_by_obid, 
introduction, 
cut, 
productEquality, 
sqequalRule, 
thin, 
productElimination, 
sqequalHypSubstitution, 
lambdaFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}g:EuclideanPlane.  \mforall{}a,b,c:Point.  \mforall{}l,m:Line.
    (a  \mneq{}  b  {}\mRightarrow{}  (a  I  l  \mwedge{}  b  I  l)  {}\mRightarrow{}  ((a  I  m  \mwedge{}  c  I  m)  \mwedge{}  c  \#  l)  {}\mRightarrow{}  b  \#  m)
 Date html generated: 
2018_05_23-PM-06_09_22
 Last ObjectModification: 
2018_05_23-AM-10_44_53
Theory : euclidean!plane!geometry
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