Nuprl Lemma : extensional-discrete-real-fun-is-constant

a,b:ℝ. ∀f:{x:ℝx ∈ [a, b]}  ⟶ ℤ.
  ∀x,y:{x:ℝx ∈ [a, b]} .  ((f x) (f y) ∈ ℤsupposing ∀x,y:{x:ℝx ∈ [a, b]} .  ((x y)  ((f x) (f y) ∈ ℤ))


Proof




Definitions occuring in Statement :  rccint: [l, u] i-member: r ∈ I req: y real: uimplies: supposing a all: x:A. B[x] implies:  Q set: {x:A| B[x]}  apply: a function: x:A ⟶ B[x] int: equal: t ∈ T
Definitions unfolded in proof :  all: x:A. B[x] member: t ∈ T uimplies: supposing a top: Top and: P ∧ Q uall: [x:A]. B[x] guard: {T} rfun: I ⟶ℝ prop: iff: ⇐⇒ Q implies:  Q real-fun: real-fun(f;a;b) uiff: uiff(P;Q) so_lambda: λ2x.t[x] so_apply: x[s] real-cont: real-cont(f;a;b) nat_plus: + less_than: a < b squash: T less_than': less_than'(a;b) true: True exists: x:A. B[x] decidable: Dec(P) or: P ∨ Q false: False not: ¬A satisfiable_int_formula: satisfiable_int_formula(fmla) rneq: x ≠ y rev_implies:  Q le: A ≤ B rleq: x ≤ y rnonneg: rnonneg(x) subtype_rel: A ⊆B nat: rdiv: (x/y) req_int_terms: t1 ≡ t2 int_seg: {i..j-} lelt: i ≤ j < k ge: i ≥  rless: x < y sq_exists: x:{A| B[x]} sq_type: SQType(T) real: sq_stable: SqStable(P) rbetween: x≤y≤z rev_uimplies: rev_uimplies(P;Q) i-member: r ∈ I rccint: [l, u] label: ...$L... t full-partition: full-partition(I;p) partition: partition(I)
Lemmas referenced :  real-fun-iff-continuous member_rccint_lemma rleq_transitivity int-to-real_wf real_wf rleq_wf i-member_wf rccint_wf req-int req_wf set_wf all_wf equal_wf less_than_wf rabs_wf rsub_wf decidable__equal_int subtract-is-int-iff full-omega-unsat intformand_wf intformnot_wf intformeq_wf itermVar_wf itermSubtract_wf itermConstant_wf int_formula_prop_and_lemma int_formula_prop_not_lemma int_formula_prop_eq_lemma int_term_value_var_lemma int_term_value_subtract_lemma int_term_value_constant_lemma int_formula_prop_wf false_wf subtract_wf rdiv_wf rless-int rless_wf rleq_functionality rabs_functionality rsub-int req_weakening rmul_preserves_rleq2 rleq-int less_than'_wf rmul_wf nat_plus_wf absval_wf nat_wf itermMultiply_wf rinv_wf2 req_transitivity squash_wf true_wf rabs-int rmul-int rmul-rinv req-iff-rsub-is-0 real_polynomial_null real_term_value_sub_lemma real_term_value_mul_lemma real_term_value_var_lemma real_term_value_const_lemma absval_unfold decidable__lt top_wf intformless_wf intformle_wf int_formula_prop_less_lemma int_formula_prop_le_lemma int_term_value_mul_lemma itermMinus_wf int_term_value_minus_lemma partition-exists rccint-icompact list_set_type full-partition_wf full-partition-point-member mesh-property int_seg_properties length_wf int_seg_wf le_wf nat_properties ge_wf decidable__le select_wf nat_plus_properties subtype_base_sq int_subtype_base sq_stable__less_than adjacent-full-partition-points lelt_wf subtract-add-cancel rbetween_wf partition-mesh_wf rabs-of-nonneg sq_stable__rleq iff_weakening_equal length_of_cons_lemma right_endpoint_rccint_lemma add_nat_plus length_wf_nat append_wf cons_wf nil_wf length-append length_of_nil_lemma add-is-int-iff itermAdd_wf int_term_value_add_lemma
Rules used in proof :  cut introduction extract_by_obid sqequalSubstitution sqequalTransitivity computationStep sqequalReflexivity lambdaFormation hypothesis sqequalHypSubstitution dependent_functionElimination thin hypothesisEquality isect_memberFormation setElimination rename isect_memberEquality voidElimination voidEquality sqequalRule independent_isectElimination productElimination isectElimination lambdaEquality applyEquality functionExtensionality setEquality productEquality independent_functionElimination dependent_set_memberEquality axiomEquality because_Cache functionEquality intEquality natural_numberEquality independent_pairFormation imageMemberEquality baseClosed unionElimination pointwiseFunctionality equalityTransitivity equalitySymmetry promote_hyp baseApply closedConclusion approximateComputation dependent_pairFormation int_eqEquality inrFormation independent_pairEquality minusEquality multiplyEquality imageElimination lessCases sqequalAxiom intWeakElimination instantiate cumulativity addEquality universeEquality applyLambdaEquality

Latex:
\mforall{}a,b:\mBbbR{}.  \mforall{}f:\{x:\mBbbR{}|  x  \mmember{}  [a,  b]\}    {}\mrightarrow{}  \mBbbZ{}.
    \mforall{}x,y:\{x:\mBbbR{}|  x  \mmember{}  [a,  b]\}  .    ((f  x)  =  (f  y)) 
    supposing  \mforall{}x,y:\{x:\mBbbR{}|  x  \mmember{}  [a,  b]\}  .    ((x  =  y)  {}\mRightarrow{}  ((f  x)  =  (f  y)))



Date html generated: 2017_10_03-AM-09_59_57
Last ObjectModification: 2017_06_01-PM-04_32_03

Theory : reals


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