Nuprl Lemma : Euclid-Prop19-lemma1
∀e:EuclideanPlane. ∀a,b,c,d:Point.  (a # bc 
⇒ bad ≅a cad 
⇒ b-d-c 
⇒ |bd| < |cd| 
⇒ |ab| < |ac|)
Proof
Definitions occuring in Statement : 
geo-cong-angle: abc ≅a xyz
, 
geo-lt: p < q
, 
geo-length: |s|
, 
geo-mk-seg: ab
, 
euclidean-plane: EuclideanPlane
, 
geo-lsep: a # bc
, 
geo-strict-between: a-b-c
, 
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
, 
guard: {T}
, 
and: P ∧ Q
, 
cand: A c∧ B
, 
subtype_rel: A ⊆r B
, 
uall: ∀[x:A]. B[x]
, 
uimplies: b supposing a
, 
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)
, 
or: P ∨ Q
, 
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
, 
euclidean-plane: EuclideanPlane
, 
uiff: uiff(P;Q)
, 
squash: ↓T
, 
true: True
, 
iff: P 
⇐⇒ Q
, 
basic-geometry-: BasicGeometry-
, 
rev_implies: P 
⇐ Q
, 
sq_exists: ∃x:A [B[x]]
, 
sq_stable: SqStable(P)
, 
geo-midpoint: a=m=b
, 
heyting-geometry: HeytingGeometry
, 
geo-triangle: a # bc
, 
geo-tri: Triangle(a;b;c)
, 
geo-lt: p < q
, 
geo-strict-between: a-b-c
Lemmas referenced : 
colinear-lsep, 
lsep-all-sym, 
geo-sep-sym, 
geo-strict-between-sep2, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
subtype_rel_transitivity, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
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, 
geo-lt_wf, 
geo-length_wf, 
geo-mk-seg_wf, 
geo-strict-between_wf, 
geo-cong-angle_wf, 
geo-lsep_wf, 
geo-point_wf, 
lsep-implies-sep, 
geo-congruent-iff-length, 
squash_wf, 
true_wf, 
geo-length-type_wf, 
basic-geometry_wf, 
subtype_rel_self, 
iff_weakening_equal, 
geo-lt-out-to-between, 
geo-out-iff-between1, 
euclidean-plane-axioms, 
geo-strict-between-sep3, 
geo-between-symmetry, 
geo-strict-between-implies-between, 
geo-length-flip, 
geo-congruent_wf, 
geo-proper-extend-exists, 
lsep-symmetry, 
colinear-lsep-cycle, 
geo-strict-between-sep1, 
outer-pasch-strict, 
geo-between-outer-trans, 
geo-between_wf, 
sq_stable__and, 
sq_stable__geo-strict-between, 
geo-midpoint-diagonals-congruent, 
vert-angles-congruent, 
Euclid-Prop4, 
geo-between-out, 
geo-out_weakening, 
geo-eq_weakening, 
geo-out_inversion, 
geo-cong-angle-symm2, 
out-cong-angle, 
geo-cong-angle-transitivity, 
out-preserves-lsep, 
Euclid-Prop6, 
out-preserves-angle-cong_1, 
geo-add-length-between, 
geo-le_weakening, 
geo-sep_wf, 
geo-le_wf, 
geo-add-length_wf, 
geo-lt_transitivity, 
geo-le_weakening-lt
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
hypothesisEquality, 
independent_functionElimination, 
because_Cache, 
hypothesis, 
productElimination, 
applyEquality, 
instantiate, 
isectElimination, 
independent_isectElimination, 
sqequalRule, 
isect_memberEquality_alt, 
voidElimination, 
dependent_set_memberEquality_alt, 
natural_numberEquality, 
independent_pairFormation, 
unionElimination, 
approximateComputation, 
dependent_pairFormation_alt, 
lambdaEquality_alt, 
universeIsType, 
productIsType, 
setElimination, 
rename, 
inhabitedIsType, 
equalitySymmetry, 
imageElimination, 
equalityTransitivity, 
imageMemberEquality, 
baseClosed, 
universeEquality
Latex:
\mforall{}e:EuclideanPlane.  \mforall{}a,b,c,d:Point.    (a  \#  bc  {}\mRightarrow{}  bad  \mcong{}\msuba{}  cad  {}\mRightarrow{}  b-d-c  {}\mRightarrow{}  |bd|  <  |cd|  {}\mRightarrow{}  |ab|  <  |ac|)
Date html generated:
2019_10_16-PM-02_16_11
Last ObjectModification:
2018_12_14-PM-00_54_26
Theory : euclidean!plane!geometry
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