Nuprl Lemma : arctangent-rtan

[x:{x:ℝx ∈ (-(π/2), π/2)} ]. (arctangent(rtan(x)) x)


Proof




Definitions occuring in Statement :  arctangent: arctangent(x) rtan: rtan(x) halfpi: π/2 rooint: (l, u) i-member: r ∈ I req: y rminus: -(x) real: uall: [x:A]. B[x] set: {x:A| B[x]} 
Definitions unfolded in proof :  cand: c∧ B exists: x:A. B[x] rtan: rtan(x) rdiv: (x/y) r-ap: f(x) rfun-eq: rfun-eq(I;f;g) req_int_terms: t1 ≡ t2 top: Top rev_uimplies: rev_uimplies(P;Q) or: P ∨ Q rneq: x ≠ y rge: x ≥ y true: True squash: T less_than: a < b rev_implies:  Q iff: ⇐⇒ Q uimplies: supposing a uiff: uiff(P;Q) not: ¬A false: False less_than': less_than'(a;b) and: P ∧ Q le: A ≤ B nat: guard: {T} so_apply: x[s] prop: rfun: I ⟶ℝ so_lambda: λ2x.t[x] implies:  Q uall: [x:A]. B[x] member: t ∈ T all: x:A. B[x]
Lemmas referenced :  rtan0 arctangent_functionality arctangent0 real_term_value_minus_lemma itermMinus_wf halfpi-positive rmul-zero-both rless_functionality rmul_reverses_rless_iff member_rooint_lemma rsin-rcos-pythag radd_comm rmul-rinv rnexp-rdiv req_inversion rsin_wf real_term_value_add_lemma real_term_value_mul_lemma rinv-as-rdiv rmul-rinv3 req_transitivity rmul-identity1 itermAdd_wf itermConstant_wf itermMultiply_wf rinv_wf2 rmul_preserves_req derivative_functionality rmul_wf real_term_value_const_lemma real_term_value_var_lemma real_term_value_sub_lemma real_polynomial_null req-iff-rsub-is-0 itermVar_wf itermSubtract_wf member_riiint_lemma all_wf rleq_wf rleq_weakening rtan_functionality_wrt_rleq rleq_functionality_wrt_implies monotone-maps-compact rdiv_functionality radd_functionality rcos_functionality rnexp_functionality req_functionality req_weakening derivative-arctangent derivative-rtan req_wf iproper-riiint rless_wf rdiv_wf riiint_wf chain-rule radd_functionality_wrt_rleq rleq_weakening_equal rless_functionality_wrt_implies rless-int trivial-rless-radd rnexp_wf radd_wf le_wf false_wf rcos_wf rnexp-positive rcos-positive rnexp2-nonneg set_wf req_witness derivative-id rtan_wf arctangent_wf i-member_wf real_wf int-to-real_wf halfpi-interval-proper halfpi_wf rminus_wf rooint_wf antiderivatives-equal
Rules used in proof :  productEquality minusEquality dependent_pairFormation intEquality int_eqEquality approximateComputation voidEquality voidElimination isect_memberEquality functionEquality inlFormation inrFormation equalitySymmetry equalityTransitivity baseClosed imageMemberEquality independent_isectElimination productElimination independent_pairFormation dependent_set_memberEquality lambdaFormation isect_memberFormation rename setElimination because_Cache hypothesisEquality setEquality natural_numberEquality lambdaEquality sqequalRule independent_functionElimination hypothesis isectElimination thin dependent_functionElimination sqequalReflexivity computationStep sqequalTransitivity sqequalSubstitution sqequalHypSubstitution extract_by_obid introduction cut

Latex:
\mforall{}[x:\{x:\mBbbR{}|  x  \mmember{}  (-(\mpi{}/2),  \mpi{}/2)\}  ].  (arctangent(rtan(x))  =  x)



Date html generated: 2018_05_22-PM-03_02_23
Last ObjectModification: 2018_05_20-PM-11_09_57

Theory : reals_2


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