Nuprl Lemma : arctangent-rtan
∀[x:{x:ℝ| x ∈ (-(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: x = y
, 
rminus: -(x)
, 
real: ℝ
, 
uall: ∀[x:A]. B[x]
, 
set: {x:A| B[x]} 
Definitions unfolded in proof : 
cand: A 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: P 
⇐ Q
, 
iff: P 
⇐⇒ Q
, 
uimplies: b supposing a
, 
uiff: uiff(P;Q)
, 
not: ¬A
, 
false: False
, 
less_than': less_than'(a;b)
, 
and: P ∧ Q
, 
le: A ≤ B
, 
nat: ℕ
, 
guard: {T}
, 
so_apply: x[s]
, 
prop: ℙ
, 
rfun: I ⟶ℝ
, 
so_lambda: λ2x.t[x]
, 
implies: P 
⇒ 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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