Nuprl Lemma : Cauchy-equation-1-iff

[f:ℝ ⟶ ℝ]
  uiff(∀x,y:ℝ.  (f(x y) (f(x) f(y)));∀x:ℝ(f(x) (x f(r1)))) supposing ∀x,y:ℝ.  ((x y)  ((f x) (f y)))


Proof




Definitions occuring in Statement :  rfun-ap: f(x) req: y rmul: b radd: b int-to-real: r(n) real: uiff: uiff(P;Q) uimplies: supposing a uall: [x:A]. B[x] all: x:A. B[x] implies:  Q apply: a function: x:A ⟶ B[x] natural_number: $n
Definitions unfolded in proof :  so_apply: x[s] so_lambda: λ2x.t[x] prop: implies:  Q all: x:A. B[x] and: P ∧ Q uiff: uiff(P;Q) uimplies: supposing a member: t ∈ T uall: [x:A]. B[x] rev_uimplies: rev_uimplies(P;Q) req_int_terms: t1 ≡ t2 nequal: a ≠ b ∈  less_than': less_than'(a;b) assert: b bnot: ¬bb sq_type: SQType(T) unit: Unit bool: 𝔹 guard: {T} or: P ∨ Q decidable: Dec(P) int-to-real: r(n) btrue: tt eq_int: (i =z j) length: ||as|| radd-list: radd-list(L) it: nil: [] bfalse: ff lt_int: i <j ifthenelse: if then else fi  from-upto: [n, m) list_ind: list_ind map: map(f;as) evalall: evalall(t) callbyvalueall: callbyvalueall subtract: m rsum: Σ{x[k] n≤k≤m} lelt: i ≤ j < k int_seg: {i..j-} le: A ≤ B top: Top exists: x:A. B[x] satisfiable_int_formula: satisfiable_int_formula(fmla) not: ¬A ge: i ≥  false: False nat: rdiv: (x/y) rev_implies:  Q iff: ⇐⇒ Q rneq: x ≠ y nat_plus: + subtype_rel: A ⊆B squash: T true: True rfun-ap: f(x) r-ap: f(x) rfun: I ⟶ℝ less_than: a < b
Lemmas referenced :  radd_wf req_wf all_wf int-to-real_wf rmul_wf rfun-ap_wf req_witness real_wf radd_functionality req_transitivity rsum_unroll real_term_value_minus_lemma real_term_value_const_lemma real_term_value_mul_lemma real_term_value_var_lemma real_term_value_add_lemma real_term_value_sub_lemma real_polynomial_null req_weakening int_term_value_add_lemma neg_assert_of_eq_int false_wf assert_of_eq_int eq_int_wf assert-bnot bool_subtype_base subtype_base_sq bool_cases_sqequal equal_wf eqff_to_assert assert_of_lt_int eqtt_to_assert bool_wf lt_int_wf itermMinus_wf req-iff-rsub-is-0 itermMultiply_wf itermAdd_wf req_inversion radd-rminus-both rminus_wf radd-preserves-req radd-zero rfun-ap_functionality req_functionality nat_wf decidable__lt int_term_value_subtract_lemma int_formula_prop_not_lemma itermSubtract_wf intformnot_wf decidable__le lelt_wf subtract-add-cancel int_seg_wf subtract_wf rsum_wf less_than_wf ge_wf int_formula_prop_wf int_formula_prop_less_lemma int_term_value_var_lemma int_term_value_constant_lemma int_formula_prop_le_lemma int_formula_prop_and_lemma intformless_wf itermVar_wf itermConstant_wf intformle_wf intformand_wf full-omega-unsat nat_properties rinv-mul-as-rdiv rmul_functionality rmul-rinv3 uiff_transitivity assert_of_bnot iff_weakening_uiff iff_transitivity bool_cases rsum-constant2 rmul_preserves_req rinv_wf2 not_wf bnot_wf assert_wf rsub_wf req-implies-req le_wf set_subtype_base rmul_comm int_formula_prop_eq_lemma intformeq_wf decidable__equal_int int_subtype_base ifthenelse_wf nat_plus_wf rless_wf nat_plus_properties rless-int rdiv_wf nat_plus_subtype_nat rdiv_functionality rmul-one radd_comm radd-rminus rminus-int true_wf squash_wf rminus_functionality rmul-rinv int_term_value_minus_lemma rminus-rminus set_wf subtype_rel_self subtype_rel_dep_function i-member_wf exists_wf rneq_wf member_riiint_lemma riiint_wf functions-equal-on-rationals rmul-distrib2
Rules used in proof :  functionEquality equalitySymmetry equalityTransitivity isect_memberEquality independent_pairEquality productElimination because_Cache independent_functionElimination natural_numberEquality applyEquality functionExtensionality isectElimination hypothesisEquality thin dependent_functionElimination lambdaEquality sqequalHypSubstitution sqequalRule hypothesis extract_by_obid lambdaFormation independent_pairFormation cut introduction isect_memberFormation sqequalReflexivity computationStep sqequalTransitivity sqequalSubstitution cumulativity instantiate promote_hyp equalityElimination unionElimination addEquality dependent_set_memberEquality voidEquality voidElimination intEquality int_eqEquality dependent_pairFormation approximateComputation independent_isectElimination intWeakElimination rename setElimination impliesFunctionality inrFormation baseClosed imageMemberEquality imageElimination minusEquality setEquality inlFormation

Latex:
\mforall{}[f:\mBbbR{}  {}\mrightarrow{}  \mBbbR{}]
    uiff(\mforall{}x,y:\mBbbR{}.    (f(x  +  y)  =  (f(x)  +  f(y)));\mforall{}x:\mBbbR{}.  (f(x)  =  (x  *  f(r1)))) 
    supposing  \mforall{}x,y:\mBbbR{}.    ((x  =  y)  {}\mRightarrow{}  ((f  x)  =  (f  y)))



Date html generated: 2017_10_04-PM-11_02_35
Last ObjectModification: 2017_07_31-PM-00_33_16

Theory : reals_2


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