Nuprl Lemma : rv-pos-angle-lemma
∀n:ℕ. ∀x,y:ℝ^n.  ((||x|| = ||y||) 
⇒ (r0 < d(x;y)) 
⇒ (r0 < d(r(-1)*x;y)) 
⇒ (|x⋅y| < (||x|| * ||y||)))
Proof
Definitions occuring in Statement : 
real-vec-dist: d(x;y)
, 
real-vec-norm: ||x||
, 
dot-product: x⋅y
, 
real-vec-mul: a*X
, 
real-vec: ℝ^n
, 
rless: x < y
, 
rabs: |x|
, 
req: x = y
, 
rmul: a * b
, 
int-to-real: r(n)
, 
nat: ℕ
, 
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]
, 
uimplies: b supposing a
, 
and: P ∧ Q
, 
prop: ℙ
, 
subtype_rel: A ⊆r B
, 
nat: ℕ
, 
le: A ≤ B
, 
less_than': less_than'(a;b)
, 
false: False
, 
not: ¬A
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
real-vec-dist: d(x;y)
, 
uiff: uiff(P;Q)
, 
rev_uimplies: rev_uimplies(P;Q)
, 
less_than: a < b
, 
squash: ↓T
, 
or: P ∨ Q
, 
rsub: x - y
, 
cand: A c∧ B
, 
nat_plus: ℕ+
, 
true: True
Lemmas referenced : 
square-rless-implies, 
rabs_wf, 
dot-product_wf, 
rmul_wf, 
real-vec-norm_wf, 
rmul-nonneg-case1, 
real-vec-norm-nonneg, 
rless_wf, 
int-to-real_wf, 
real-vec-dist_wf, 
real-vec-mul_wf, 
real_wf, 
rleq_wf, 
req_wf, 
real-vec_wf, 
nat_wf, 
rnexp_wf, 
false_wf, 
le_wf, 
rnexp2-nonneg, 
rless_functionality, 
req_inversion, 
rabs-rnexp, 
rnexp-rmul, 
rabs-of-nonneg, 
rmul_functionality, 
real-vec-norm-squared, 
rnexp2, 
req_weakening, 
rnexp-positive, 
real-vec-sub_wf, 
radd_wf, 
real-vec-norm-diff-squared, 
radd_functionality, 
dot-product-linearity2, 
req_transitivity, 
rmul-assoc, 
rmul-int, 
rmul-one-both, 
radd-assoc, 
radd_comm, 
req_functionality, 
rnexp_functionality, 
radd-preserves-req, 
rsub_wf, 
rminus_wf, 
rmul-is-positive, 
rless-int, 
less_than_wf, 
or_wf, 
uiff_transitivity, 
rmul-identity1, 
rmul-distrib2, 
radd-int, 
rmul-distrib, 
rmul_over_rminus, 
radd-ac, 
radd-rminus-both, 
radd-zero-both, 
rmul-zero-both, 
radd-preserves-rless, 
rabs-rless-iff, 
rminus-as-rmul, 
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, 
independent_functionElimination, 
independent_isectElimination, 
independent_pairFormation, 
because_Cache, 
natural_numberEquality, 
minusEquality, 
applyEquality, 
lambdaEquality, 
setElimination, 
rename, 
setEquality, 
sqequalRule, 
dependent_set_memberEquality, 
productElimination, 
multiplyEquality, 
promote_hyp, 
addEquality, 
addLevel, 
orFunctionality, 
andLevelFunctionality, 
imageElimination, 
voidElimination, 
productEquality, 
unionElimination, 
imageMemberEquality, 
baseClosed
Latex:
\mforall{}n:\mBbbN{}.  \mforall{}x,y:\mBbbR{}\^{}n.
    ((||x||  =  ||y||)  {}\mRightarrow{}  (r0  <  d(x;y))  {}\mRightarrow{}  (r0  <  d(r(-1)*x;y))  {}\mRightarrow{}  (|x\mcdot{}y|  <  (||x||  *  ||y||)))
Date html generated:
2017_10_03-AM-11_06_12
Last ObjectModification:
2017_03_02-PM-04_07_58
Theory : reals
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