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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