Nuprl Lemma : real-vec-angle-lemma
∀n:ℕ. ∀x,z:ℝ^n.  (d(z;x) < d(z;r(-1)*x) ⇐⇒ r0 < x⋅z)
Proof
Definitions occuring in Statement : 
real-vec-dist: d(x;y), 
dot-product: x⋅y, 
real-vec-mul: a*X, 
real-vec: ℝ^n, 
rless: x < y, 
int-to-real: r(n), 
nat: ℕ, 
all: ∀x:A. B[x], 
iff: P ⇐⇒ Q, 
minus: -n, 
natural_number: $n
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
real-vec-dist: d(x;y), 
real-vec-norm: ||x||, 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
member: t ∈ T, 
uall: ∀[x:A]. B[x], 
prop: ℙ, 
rev_implies: P ⇐ Q, 
implies: P ⇒ Q, 
subtype_rel: A ⊆r B, 
uimplies: b supposing a, 
uiff: uiff(P;Q), 
req_int_terms: t1 ≡ t2, 
false: False, 
not: ¬A, 
top: Top, 
less_than: a < b, 
squash: ↓T, 
less_than': less_than'(a;b), 
true: True
Lemmas referenced : 
rsqrt-rless-iff, 
dot-product-nonneg, 
real-vec-sub_wf, 
dot-product_wf, 
rleq_wf, 
int-to-real_wf, 
real-vec-mul_wf, 
rless_wf, 
rsqrt_wf, 
real_wf, 
req_wf, 
rmul_wf, 
iff_wf, 
real-vec_wf, 
nat_wf, 
dot-product-comm, 
radd_wf, 
rless_functionality, 
rsub_wf, 
itermSubtract_wf, 
itermVar_wf, 
itermAdd_wf, 
itermMultiply_wf, 
itermConstant_wf, 
req-iff-rsub-is-0, 
req_transitivity, 
dot-product-linearity1-sub, 
rsub_functionality, 
req_weakening, 
dot-product-linearity2, 
rmul_functionality, 
real_polynomial_null, 
real_term_value_sub_lemma, 
real_term_value_var_lemma, 
real_term_value_add_lemma, 
real_term_value_mul_lemma, 
real_term_value_const_lemma, 
radd-preserves-rless, 
rmul_preserves_rless, 
rless-int, 
rmul-zero-both, 
rmul_comm
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
cut, 
addLevel, 
sqequalHypSubstitution, 
productElimination, 
thin, 
independent_pairFormation, 
impliesFunctionality, 
introduction, 
extract_by_obid, 
dependent_functionElimination, 
isectElimination, 
hypothesisEquality, 
hypothesis, 
dependent_set_memberEquality, 
natural_numberEquality, 
because_Cache, 
minusEquality, 
independent_functionElimination, 
applyEquality, 
sqequalRule, 
lambdaEquality, 
setElimination, 
rename, 
setEquality, 
productEquality, 
independent_isectElimination, 
approximateComputation, 
int_eqEquality, 
intEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
imageMemberEquality, 
baseClosed
Latex:
\mforall{}n:\mBbbN{}.  \mforall{}x,z:\mBbbR{}\^{}n.    (d(z;x)  <  d(z;r(-1)*x)  \mLeftarrow{}{}\mRightarrow{}  r0  <  x\mcdot{}z)
 Date html generated: 
2018_05_22-PM-02_25_51
 Last ObjectModification: 
2018_03_27-PM-10_36_41
Theory : reals
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