Nuprl Lemma : rsub-int-fractions
∀[a,b:ℤ]. ∀[c,d:ℕ+].  (((r(a)/r(c)) - (r(b)/r(d))) = (r((a * d) - b * c)/r(c * d)))
Proof
Definitions occuring in Statement : 
rdiv: (x/y), 
rsub: x - y, 
req: x = y, 
int-to-real: r(n), 
nat_plus: ℕ+, 
uall: ∀[x:A]. B[x], 
multiply: n * m, 
subtract: n - m, 
int: ℤ
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
nat_plus: ℕ+, 
uimplies: b supposing a, 
rneq: x ≠ y, 
guard: {T}, 
or: P ∨ Q, 
all: ∀x:A. B[x], 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
rev_implies: P ⇐ Q, 
implies: P ⇒ Q, 
decidable: Dec(P), 
not: ¬A, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
false: False, 
prop: ℙ, 
true: True, 
subtract: n - m, 
squash: ↓T, 
subtype_rel: A ⊆r B, 
rsub: x - y, 
uiff: uiff(P;Q), 
rev_uimplies: rev_uimplies(P;Q)
Latex:
\mforall{}[a,b:\mBbbZ{}].  \mforall{}[c,d:\mBbbN{}\msupplus{}].    (((r(a)/r(c))  -  (r(b)/r(d)))  =  (r((a  *  d)  -  b  *  c)/r(c  *  d)))
 Date html generated: 
2020_05_20-AM-11_00_43
 Last ObjectModification: 
2020_01_03-AM-11_17_22
Theory : reals
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