Nuprl Lemma : real-vec-norm-diff-bound
∀[n:ℕ]. ∀[x,y:ℝ^n].  (|||x|| - ||y||| ≤ d(x;y))
Proof
Definitions occuring in Statement : 
real-vec-dist: d(x;y), 
real-vec-norm: ||x||, 
real-vec: ℝ^n, 
rleq: x ≤ y, 
rabs: |x|, 
rsub: x - y, 
nat: ℕ, 
uall: ∀[x:A]. B[x]
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
real-vec: ℝ^n, 
int_seg: {i..j-}, 
lelt: i ≤ j < k, 
and: P ∧ Q, 
le: A ≤ B, 
nat: ℕ, 
rleq: x ≤ y, 
rnonneg: rnonneg(x), 
all: ∀x:A. B[x], 
uimplies: b supposing a, 
subtype_rel: A ⊆r B, 
uiff: uiff(P;Q), 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
implies: P ⇒ Q, 
cand: A c∧ B, 
squash: ↓T, 
prop: ℙ, 
true: True, 
guard: {T}, 
req_int_terms: t1 ≡ t2, 
false: False, 
not: ¬A, 
top: Top
Lemmas referenced : 
real-vec-triangle-inequality, 
int-to-real_wf, 
int_seg_wf, 
le_witness_for_triv, 
real-vec_wf, 
istype-nat, 
real-vec-dist_wf, 
real-vec-norm_wf, 
radd_wf, 
rleq_functionality, 
real-vec-dist-from-zero, 
radd_functionality, 
req_weakening, 
rabs-difference-bound-rleq, 
rleq-implies-rleq, 
rsub_wf, 
rleq_wf, 
squash_wf, 
true_wf, 
real_wf, 
radd_comm_eq, 
subtype_rel_self, 
iff_weakening_equal, 
itermSubtract_wf, 
itermAdd_wf, 
itermVar_wf, 
req-iff-rsub-is-0, 
real-vec-dist-symmetry, 
real_polynomial_null, 
istype-int, 
real_term_value_sub_lemma, 
istype-void, 
real_term_value_add_lemma, 
real_term_value_var_lemma, 
real_term_value_const_lemma
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality_alt, 
setElimination, 
rename, 
productElimination, 
hypothesis, 
universeIsType, 
natural_numberEquality, 
dependent_functionElimination, 
equalityTransitivity, 
equalitySymmetry, 
independent_isectElimination, 
functionIsTypeImplies, 
inhabitedIsType, 
isect_memberEquality_alt, 
isectIsTypeImplies, 
because_Cache, 
applyEquality, 
independent_functionElimination, 
independent_pairFormation, 
imageElimination, 
imageMemberEquality, 
baseClosed, 
instantiate, 
universeEquality, 
approximateComputation, 
int_eqEquality, 
voidElimination
Latex:
\mforall{}[n:\mBbbN{}].  \mforall{}[x,y:\mBbbR{}\^{}n].    (|||x||  -  ||y|||  \mleq{}  d(x;y))
Date html generated:
2019_10_30-AM-08_42_49
Last ObjectModification:
2019_07_08-AM-11_35_44
Theory : reals
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