Nuprl Lemma : Euclid-drop-perp-1
∀e:EuclideanPlane. ∀a:Point. ∀b:{b:Point| a ≠ b} . ∀c:{c:Point| ∀x:Point. (Colinear(a;b;x) ⇒ c ≠ x)} .
  ∃p:Point. (Colinear(a;b;p) ∧ ab  ⊥p pc)
Proof
Definitions occuring in Statement : 
geo-perp-in: ab  ⊥x cd, 
euclidean-plane: EuclideanPlane, 
geo-colinear: Colinear(a;b;c), 
geo-sep: a ≠ b, 
geo-point: Point, 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
implies: P ⇒ Q, 
and: P ∧ Q, 
set: {x:A| B[x]} 
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
member: t ∈ T, 
exists: ∃x:A. B[x], 
sq_exists: ∃x:A [B[x]], 
and: P ∧ Q, 
cand: A c∧ B, 
subtype_rel: A ⊆r B, 
uall: ∀[x:A]. B[x], 
guard: {T}, 
uimplies: b supposing a, 
sq_stable: SqStable(P), 
implies: P ⇒ Q, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
geo-perp-in: ab  ⊥x cd, 
squash: ↓T, 
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, 
le: A ≤ B, 
less_than': less_than'(a;b), 
false: False, 
not: ¬A, 
prop: ℙ, 
less_than: a < b, 
true: True, 
select: L[n], 
cons: [a / b], 
subtract: n - m, 
so_lambda: λ2x.t[x], 
so_apply: x[s]
Lemmas referenced : 
Euclid-drop-perp-0, 
sq_stable__colinear, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
subtype_rel_transitivity, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
euclidean-plane-axioms, 
sq_stable__from_stable, 
geo-perp-in_wf, 
stable__geo-perp-in, 
geo-perp-in-iff2, 
geo-colinear-is-colinear-set, 
length_of_cons_lemma, 
length_of_nil_lemma, 
false_wf, 
lelt_wf, 
geo-colinear_wf, 
geo-point_wf, 
all_wf, 
geo-sep_wf
Rules used in proof : 
cut, 
introduction, 
extract_by_obid, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
hypothesis, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
hypothesisEquality, 
setElimination, 
rename, 
productElimination, 
dependent_pairFormation, 
applyEquality, 
instantiate, 
isectElimination, 
independent_isectElimination, 
sqequalRule, 
independent_functionElimination, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
independent_pairFormation, 
because_Cache, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
dependent_set_memberEquality, 
natural_numberEquality, 
productEquality, 
setEquality, 
lambdaEquality, 
functionEquality
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}a:Point.  \mforall{}b:\{b:Point|  a  \mneq{}  b\}  .
\mforall{}c:\{c:Point|  \mforall{}x:Point.  (Colinear(a;b;x)  {}\mRightarrow{}  c  \mneq{}  x)\}  .
    \mexists{}p:Point.  (Colinear(a;b;p)  \mwedge{}  ab    \mbot{}p  pc)
Date html generated:
2018_05_22-PM-00_11_58
Last ObjectModification:
2018_05_11-PM-03_22_52
Theory : euclidean!plane!geometry
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