Nuprl Lemma : rv-orthogonal-iff-norm-preserving
∀[rv:InnerProductSpace]
  ∀f:Point ⟶ Point
    (Orthogonal(f) ⇐⇒ (∀x,y:Point.  f x + y ≡ f x + f y) ∧ (∀x:Point. ((∀a:ℝ. f a*x ≡ a*f x) ∧ (||f x|| = ||x||))))
Proof
Definitions occuring in Statement : 
rv-orthogonal: Orthogonal(f), 
rv-norm: ||x||, 
inner-product-space: InnerProductSpace, 
rv-mul: a*x, 
rv-add: x + y, 
ss-eq: x ≡ y, 
ss-point: Point, 
req: x = y, 
real: ℝ, 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x], 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
apply: f a, 
function: x:A ⟶ B[x]
Definitions unfolded in proof : 
true: True, 
squash: ↓T, 
less_than: a < b, 
or: P ∨ Q, 
rneq: x ≠ y, 
rsub: x - y, 
rv-minus: -x, 
rv-sub: x - y, 
less_than': less_than'(a;b), 
le: A ≤ B, 
nat: ℕ, 
cand: A c∧ B, 
rev_uimplies: rev_uimplies(P;Q), 
uiff: uiff(P;Q), 
rv-norm: ||x||, 
rv-orthogonal: Orthogonal(f), 
false: False, 
not: ¬A, 
ss-eq: x ≡ y, 
so_apply: x[s], 
so_lambda: λ2x.t[x], 
rev_implies: P ⇐ Q, 
prop: ℙ, 
uimplies: b supposing a, 
guard: {T}, 
subtype_rel: A ⊆r B, 
implies: P ⇒ Q, 
and: P ∧ Q, 
iff: P ⇐⇒ Q, 
all: ∀x:A. B[x], 
member: t ∈ T, 
uall: ∀[x:A]. B[x]
Lemmas referenced : 
rmul_comm, 
rless_wf, 
rless-int, 
rmul_preserves_req, 
radd-zero-both, 
rmul-zero-both, 
radd-int, 
rmul_functionality, 
rminus-as-rmul, 
rmul-distrib2, 
rmul-identity1, 
radd-rminus-assoc, 
radd_comm, 
radd-ac, 
radd-assoc, 
rminus-radd, 
rminus_wf, 
radd-preserves-req, 
rsub_functionality, 
radd_functionality, 
rv-ip-sub-squared, 
rsub_wf, 
radd_wf, 
rv-sub_wf, 
ss-eq_inversion, 
ss-eq_weakening, 
rv-add_functionality, 
rv-ip_functionality, 
uiff_transitivity, 
rnexp_functionality, 
req_transitivity, 
rv-norm-squared, 
le_wf, 
false_wf, 
rnexp_wf, 
req_inversion, 
rsqrt_functionality, 
req_functionality, 
req_weakening, 
rv-ip-nonneg, 
rsqrt_wf, 
req_witness, 
ss-sep_wf, 
rv-ip_wf, 
rmul_wf, 
int-to-real_wf, 
rleq_wf, 
rv-norm_wf, 
req_wf, 
rv-mul_wf, 
rv-add_wf, 
ss-eq_wf, 
all_wf, 
rv-orthogonal_wf, 
real_wf, 
separation-space_wf, 
real-vector-space_wf, 
inner-product-space_wf, 
subtype_rel_transitivity, 
inner-product-space_subtype, 
real-vector-space_subtype1, 
ss-point_wf
Rules used in proof : 
baseClosed, 
imageMemberEquality, 
inrFormation, 
addEquality, 
promote_hyp, 
allFunctionality, 
minusEquality, 
dependent_set_memberEquality, 
independent_functionElimination, 
voidElimination, 
independent_pairEquality, 
functionEquality, 
natural_numberEquality, 
setEquality, 
rename, 
setElimination, 
lambdaEquality, 
productEquality, 
productElimination, 
functionExtensionality, 
dependent_functionElimination, 
because_Cache, 
sqequalRule, 
independent_isectElimination, 
instantiate, 
hypothesis, 
applyEquality, 
hypothesisEquality, 
thin, 
isectElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
independent_pairFormation, 
lambdaFormation, 
cut, 
introduction, 
isect_memberFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}[rv:InnerProductSpace]
    \mforall{}f:Point  {}\mrightarrow{}  Point
        (Orthogonal(f)
        \mLeftarrow{}{}\mRightarrow{}  (\mforall{}x,y:Point.    f  x  +  y  \mequiv{}  f  x  +  f  y)
                \mwedge{}  (\mforall{}x:Point.  ((\mforall{}a:\mBbbR{}.  f  a*x  \mequiv{}  a*f  x)  \mwedge{}  (||f  x||  =  ||x||))))
Date html generated:
2016_11_08-AM-09_18_07
Last ObjectModification:
2016_11_01-AM-00_25_56
Theory : inner!product!spaces
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