Nuprl Lemma : isosc-bisectors-between
∀e:HeytingGeometry. ∀a,b,c,m,a',b',m':Point.
  (c # ab ⇒ ac ≅ bc ⇒ (c-a-a' ∧ b'-b-c) ⇒ a=m=b ⇒ a'=m'=b' ⇒ aa' ≅ bb' ⇒ c-m-m')
Proof
Definitions occuring in Statement : 
geo-triangle: a # bc, 
heyting-geometry: HeytingGeometry, 
geo-midpoint: a=m=b, 
geo-strict-between: a-b-c, 
geo-congruent: ab ≅ cd, 
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, 
guard: {T}, 
cand: A c∧ B, 
heyting-geometry: HeytingGeometry, 
subtype_rel: A ⊆r B, 
euclidean-plane: EuclideanPlane, 
basic-geometry: BasicGeometry, 
uall: ∀[x:A]. B[x], 
uimplies: b supposing a, 
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, 
squash: ↓T, 
true: True, 
select: L[n], 
cons: [a / b], 
subtract: n - m, 
geo-midpoint: a=m=b, 
geo-strict-between: a-b-c, 
uiff: uiff(P;Q), 
basic-geometry-: BasicGeometry-, 
exists: ∃x:A. B[x], 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q
Lemmas referenced : 
geo-triangle-colinear, 
geo-triangle-symmetry, 
geo-sep-sym, 
geo-strict-between-sep1, 
geo-colinear-is-colinear-set, 
geo-strict-between-implies-colinear, 
subtype_rel_self, 
geo-triangle-property, 
length_of_cons_lemma, 
length_of_nil_lemma, 
false_wf, 
lelt_wf, 
midpoint-sep, 
geo-between-implies-colinear, 
geo-congruent_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
heyting-geometry-subtype, 
subtype_rel_transitivity, 
heyting-geometry_wf, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-midpoint_wf, 
basic-geo-axioms_wf, 
geo-left-axioms_wf, 
geo-strict-between_wf, 
geo-triangle_wf, 
geo-point_wf, 
geo-add-length-between, 
geo-congruent-iff-length, 
geo-length-flip, 
geo-add-length_wf, 
squash_wf, 
true_wf, 
geo-length-type_wf, 
basic-geometry_wf, 
geo-add-length-comm, 
isosceles-mid-exists, 
geo-strict-between-sep3, 
geo-proper-extend-exists, 
geo-krippen-lemma, 
geo-between-symmetry, 
geo-strict-between-implies-between, 
geo-between-exchange3, 
geo-between-exchange4, 
geo-between-inner-trans, 
geo-congruent-symmetry, 
geo-midpoint-symmetry, 
geo-out-iff-between1, 
geo-out-colinear, 
geo-strict-between-sym, 
double-pasch-exists, 
geo-intersection-unicity, 
geo-colinear_wf, 
not-geo-triangle-iff-colinear, 
geo-eq_weakening, 
geo-strict-between_functionality
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
sqequalHypSubstitution, 
productElimination, 
thin, 
cut, 
introduction, 
extract_by_obid, 
dependent_functionElimination, 
hypothesisEquality, 
because_Cache, 
independent_functionElimination, 
hypothesis, 
applyEquality, 
sqequalRule, 
instantiate, 
isectElimination, 
independent_isectElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
dependent_set_memberEquality, 
natural_numberEquality, 
independent_pairFormation, 
imageMemberEquality, 
baseClosed, 
setEquality, 
productEquality, 
cumulativity, 
equalityTransitivity, 
equalitySymmetry, 
lambdaEquality, 
imageElimination, 
rename
Latex:
\mforall{}e:HeytingGeometry.  \mforall{}a,b,c,m,a',b',m':Point.
    (c  \#  ab  {}\mRightarrow{}  ac  \00D0  bc  {}\mRightarrow{}  (c-a-a'  \mwedge{}  b'-b-c)  {}\mRightarrow{}  a=m=b  {}\mRightarrow{}  a'=m'=b'  {}\mRightarrow{}  aa'  \00D0  bb'  {}\mRightarrow{}  c-m-m')
Date html generated:
2017_10_02-PM-07_06_23
Last ObjectModification:
2017_08_16-PM-00_17_13
Theory : euclidean!plane!geometry
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