Nuprl Lemma : m-ball-boundary-subtype-m-sphere
∀[X:Type]. ∀[d:metric(X)]. ∀[c:X]. ∀[r:ℝ].  (m-boundary(X;d;m-ball(X;d;c;r)) ⊆r m-sphere(X;d;c;r))
Proof
Definitions occuring in Statement : 
m-sphere: m-sphere(X;d;c;r), 
m-ball: m-ball(X;d;c;r), 
m-boundary: m-boundary(X;d;A), 
metric: metric(X), 
real: ℝ, 
subtype_rel: A ⊆r B, 
uall: ∀[x:A]. B[x], 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
subtype_rel: A ⊆r B, 
m-boundary: m-boundary(X;d;A), 
m-sphere: m-sphere(X;d;c;r), 
m-ball: m-ball(X;d;c;r), 
uimplies: b supposing a, 
not: ¬A, 
implies: P ⇒ Q, 
rneq: x ≠ y, 
or: P ∨ Q, 
all: ∀x:A. B[x], 
prop: ℙ, 
m-interior-point: m-interior-point(X;d;A;p), 
exists: ∃x:A. B[x], 
nat_plus: ℕ+, 
guard: {T}, 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
rev_implies: P ⇐ Q, 
rless: x < y, 
sq_exists: ∃x:A [B[x]], 
decidable: Dec(P), 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
false: False, 
top: Top, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
respects-equality: respects-equality(S;T), 
uiff: uiff(P;Q), 
req_int_terms: t1 ≡ t2, 
rev_uimplies: rev_uimplies(P;Q), 
rge: x ≥ y
Latex:
\mforall{}[X:Type].  \mforall{}[d:metric(X)].  \mforall{}[c:X].  \mforall{}[r:\mBbbR{}].    (m-boundary(X;d;m-ball(X;d;c;r))  \msubseteq{}r  m-sphere(X;d;c;r))
 Date html generated: 
2020_05_20-AM-11_47_08
 Last ObjectModification: 
2019_11_07-AM-10_54_08
Theory : reals
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