Nuprl Lemma : ip-triangle-lemma
∀rv:InnerProductSpace. ∀x,y:Point.
  ((||x|| = ||y||) ⇒ (r0 < ||x - y||) ⇒ (r0 < ||r(-1)*x - y||) ⇒ (|x ⋅ y| < (||x|| * ||y||)))
Proof
Definitions occuring in Statement : 
rv-norm: ||x||, 
rv-sub: x - y, 
rv-ip: x ⋅ y, 
inner-product-space: InnerProductSpace, 
rv-mul: a*x, 
rless: x < y, 
rabs: |x|, 
req: x = y, 
rmul: a * b, 
int-to-real: r(n), 
ss-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
minus: -n, 
natural_number: $n
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
member: t ∈ T, 
uall: ∀[x:A]. B[x], 
subtype_rel: A ⊆r B, 
and: P ∧ Q, 
prop: ℙ, 
uimplies: b supposing a, 
guard: {T}, 
nat: ℕ, 
le: A ≤ B, 
less_than': less_than'(a;b), 
false: False, 
not: ¬A, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
itermConstant: "const", 
req_int_terms: t1 ≡ t2, 
top: Top, 
uiff: uiff(P;Q), 
rev_uimplies: rev_uimplies(P;Q), 
less_than: a < b, 
squash: ↓T, 
or: P ∨ Q, 
cand: A c∧ B, 
nat_plus: ℕ+, 
true: True
Lemmas referenced : 
square-rless-implies, 
rabs_wf, 
rv-ip_wf, 
rmul_wf, 
rv-norm_wf, 
real_wf, 
rleq_wf, 
int-to-real_wf, 
req_wf, 
rmul-nonneg-case1, 
rv-norm-nonneg, 
rless_wf, 
rv-sub_wf, 
inner-product-space_subtype, 
rv-mul_wf, 
ss-point_wf, 
real-vector-space_subtype1, 
subtype_rel_transitivity, 
inner-product-space_wf, 
real-vector-space_wf, 
separation-space_wf, 
rnexp_wf, 
false_wf, 
le_wf, 
rnexp2-nonneg, 
rnexp-positive, 
radd_wf, 
rsub_wf, 
rless_functionality, 
req_inversion, 
rabs-rnexp, 
rnexp-rmul, 
rabs-of-nonneg, 
rmul_functionality, 
rv-norm-squared, 
rnexp2, 
req_weakening, 
req_transitivity, 
rv-ip-sub-squared, 
radd_functionality, 
rsub_functionality, 
rv-ip-mul, 
rv-ip-mul2, 
rmul-assoc, 
rmul-int, 
real_term_polynomial, 
itermSubtract_wf, 
itermAdd_wf, 
itermMultiply_wf, 
itermConstant_wf, 
itermVar_wf, 
real_term_value_const_lemma, 
real_term_value_sub_lemma, 
real_term_value_add_lemma, 
real_term_value_mul_lemma, 
real_term_value_var_lemma, 
req-iff-rsub-is-0, 
req_functionality, 
rnexp_functionality, 
radd-preserves-req, 
rmul-is-positive, 
rless-int, 
less_than_wf, 
or_wf, 
radd-preserves-rless, 
rminus_wf, 
rabs-rless-iff, 
itermMinus_wf, 
real_term_value_minus_lemma, 
rnexp-rless, 
zero-rleq-rabs
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
isectElimination, 
hypothesisEquality, 
hypothesis, 
applyEquality, 
lambdaEquality, 
setElimination, 
rename, 
setEquality, 
productEquality, 
natural_numberEquality, 
sqequalRule, 
independent_functionElimination, 
because_Cache, 
independent_isectElimination, 
independent_pairFormation, 
minusEquality, 
instantiate, 
dependent_set_memberEquality, 
productElimination, 
multiplyEquality, 
promote_hyp, 
computeAll, 
int_eqEquality, 
intEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
addLevel, 
orFunctionality, 
andLevelFunctionality, 
imageElimination, 
unionElimination, 
imageMemberEquality, 
baseClosed
Latex:
\mforall{}rv:InnerProductSpace.  \mforall{}x,y:Point.
    ((||x||  =  ||y||)  {}\mRightarrow{}  (r0  <  ||x  -  y||)  {}\mRightarrow{}  (r0  <  ||r(-1)*x  -  y||)  {}\mRightarrow{}  (|x  \mcdot{}  y|  <  (||x||  *  ||y||)))
Date html generated:
2017_10_04-PM-11_59_17
Last ObjectModification:
2017_07_28-AM-08_54_41
Theory : inner!product!spaces
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