Nuprl Lemma : Euclid-Prop28_1
∀e:EuclideanPlane. ∀a,b,c,d,x,y,p:Point.
  (((Colinear(x;a;b) ∧ Colinear(y;c;d)) ∧ (a leftof yx ∧ a-x-b) ∧ (c leftof xy ∧ c-y-d) ∧ p-x-y ∧ bxp ≅a cyx)
  ⇒ geo-parallel-points(e;a;b;c;d))
Proof
Definitions occuring in Statement : 
geo-parallel-points: geo-parallel-points(e;a;b;c;d), 
geo-cong-angle: abc ≅a xyz, 
euclidean-plane: EuclideanPlane, 
geo-colinear: Colinear(a;b;c), 
geo-strict-between: a-b-c, 
geo-left: a leftof bc, 
geo-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
and: P ∧ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
and: P ∧ Q, 
member: t ∈ T, 
heyting-geometry: HeytingGeometry, 
basic-geometry-: BasicGeometry-, 
geo-triangle: a # bc, 
uall: ∀[x:A]. B[x], 
subtype_rel: A ⊆r B, 
guard: {T}, 
uimplies: b supposing a, 
prop: ℙ, 
basic-geometry: BasicGeometry, 
cand: A c∧ B, 
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), 
or: P ∨ Q, 
not: ¬A, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
false: False, 
select: L[n], 
cons: [a / b], 
subtract: n - m
Lemmas referenced : 
vert-angles-congruent, 
geo-strict-between-sym, 
geo-colinear_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
subtype_rel_transitivity, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-left_wf, 
geo-strict-between_wf, 
geo-cong-angle_wf, 
geo-point_wf, 
colinear-lsep-cycle, 
lsep-all-sym2, 
geo-strict-between-sep2, 
geo-colinear-is-colinear-set, 
geo-strict-between-implies-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, 
lsep-all-sym, 
colinear-lsep, 
geo-sep-sym, 
geo-strict-between-sep3, 
Euclid-Prop27, 
euclidean-plane-axioms, 
left-implies-sep, 
geo-cong-angle-symm2, 
geo-cong-angle-transitivity
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
sqequalHypSubstitution, 
productElimination, 
thin, 
cut, 
introduction, 
extract_by_obid, 
dependent_functionElimination, 
sqequalRule, 
hypothesisEquality, 
independent_functionElimination, 
because_Cache, 
hypothesis, 
productIsType, 
universeIsType, 
isectElimination, 
applyEquality, 
instantiate, 
independent_isectElimination, 
inhabitedIsType, 
isect_memberEquality_alt, 
voidElimination, 
dependent_set_memberEquality_alt, 
natural_numberEquality, 
independent_pairFormation, 
unionElimination, 
approximateComputation, 
dependent_pairFormation_alt, 
lambdaEquality_alt
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}a,b,c,d,x,y,p:Point.
    (((Colinear(x;a;b)  \mwedge{}  Colinear(y;c;d))
    \mwedge{}  (a  leftof  yx  \mwedge{}  a-x-b)
    \mwedge{}  (c  leftof  xy  \mwedge{}  c-y-d)
    \mwedge{}  p-x-y
    \mwedge{}  bxp  \mcong{}\msuba{}  cyx)
    {}\mRightarrow{}  geo-parallel-points(e;a;b;c;d))
 Date html generated: 
2019_10_16-PM-02_38_00
 Last ObjectModification: 
2019_08_24-PM-06_48_55
Theory : euclidean!plane!geometry
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