Nuprl Lemma : rcos-is-1-iff
∀x:ℝ. (rcos(x) = r1 ⇐⇒ ∃n:ℤ. (x = 2 * n * π))
Proof
Definitions occuring in Statement : 
pi: π, 
rcos: rcos(x), 
int-rmul: k1 * a, 
req: x = y, 
int-to-real: r(n), 
real: ℝ, 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
iff: P ⇐⇒ Q, 
multiply: n * m, 
natural_number: $n, 
int: ℤ
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
nat: ℕ, 
false: False, 
ge: i ≥ j , 
uimplies: b supposing a, 
not: ¬A, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
top: Top, 
and: P ∧ Q, 
prop: ℙ, 
rleq: x ≤ y, 
rnonneg: rnonneg(x), 
le: A ≤ B, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
uiff: uiff(P;Q), 
req_int_terms: t1 ≡ t2, 
true: True, 
rev_uimplies: rev_uimplies(P;Q), 
squash: ↓T, 
guard: {T}, 
rge: x ≥ y, 
rless: x < y, 
sq_exists: ∃x:A [B[x]], 
nat_plus: ℕ+, 
decidable: Dec(P), 
or: P ∨ Q, 
less_than: a < b, 
less_than': less_than'(a;b), 
int-to-real: r(n), 
int-rmul: k1 * a, 
pi: π, 
halfpi: π/2, 
divide: n ÷ m, 
cubic_converge: cubic_converge(b;m), 
ifthenelse: if b then t else f fi , 
le_int: i ≤z j, 
bnot: ¬bb, 
lt_int: i <z j, 
bfalse: ff, 
btrue: tt, 
fastpi: fastpi(n), 
primrec: primrec(n;b;c), 
primtailrec: primtailrec(n;i;b;f), 
subtype_rel: A ⊆r B, 
real: ℝ, 
rneq: x ≠ y, 
rdiv: (x/y), 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
rat_term_to_real: rat_term_to_real(f;t), 
rtermMultiply: left "*" right, 
rat_term_ind: rat_term_ind, 
rtermVar: rtermVar(var), 
rtermDivide: num "/" denom, 
pi1: fst(t), 
pi2: snd(t)
Lemmas referenced : 
nat_properties, 
full-omega-unsat, 
intformand_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformless_wf, 
istype-int, 
int_formula_prop_and_lemma, 
istype-void, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_less_lemma, 
int_formula_prop_wf, 
ge_wf, 
istype-less_than, 
le_witness_for_triv, 
subtract-1-ge-0, 
istype-nat, 
req_wf, 
rcos_wf, 
int-to-real_wf, 
real_wf, 
rcos-1-implies-at-least-2pi, 
rless_wf, 
rmul_wf, 
int-rmul_wf, 
pi_wf, 
itermSubtract_wf, 
itermMultiply_wf, 
rleq_wf, 
radd_wf, 
itermAdd_wf, 
rless_functionality, 
req_weakening, 
iff_weakening_uiff, 
rleq_functionality, 
req_transitivity, 
rmul_functionality, 
req_inversion, 
radd-int, 
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, 
real_term_value_add_lemma, 
rcos-shift-2n-pi, 
rsub_wf, 
rcos_functionality, 
rminus_wf, 
itermMinus_wf, 
req_functionality, 
squash_wf, 
true_wf, 
rminus-int, 
real_term_value_minus_lemma, 
rless-implies-rless, 
radd-preserves-rleq, 
rleq_weakening_equal, 
rleq_functionality_wrt_implies, 
rabs_wf, 
rcos-is-1, 
rcos-rabs, 
decidable__lt, 
intformnot_wf, 
int_formula_prop_not_lemma, 
rleq_weakening_rless, 
rmul_preserves_rless, 
rdiv_wf, 
rmul_preserves_rleq, 
rinv_wf2, 
rless_transitivity1, 
rleq_weakening, 
rabs-of-nonneg, 
rabs-rdiv, 
rdiv_functionality, 
rmul-rinv3, 
r-archimedean-rabs-ext, 
subtract_wf, 
primrec-wf2, 
rleq_antisymmetry, 
zero-rleq-rabs, 
rabs-is-zero, 
rless-cases, 
rless-int, 
int_term_value_subtract_lemma, 
nat_plus_properties, 
decidable__le, 
istype-le, 
subtract-add-cancel, 
rabs-of-nonpos, 
not-rless, 
rless_transitivity2, 
rmul_preserves_req, 
rminus-as-rmul, 
rless_irreflexivity, 
assert-rat-term-eq2, 
rtermVar_wf, 
rtermMultiply_wf, 
rtermDivide_wf, 
int-rmul-req, 
rmul-int
Rules used in proof : 
cut, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
setElimination, 
rename, 
intWeakElimination, 
natural_numberEquality, 
independent_isectElimination, 
approximateComputation, 
independent_functionElimination, 
dependent_pairFormation_alt, 
lambdaEquality_alt, 
int_eqEquality, 
dependent_functionElimination, 
isect_memberEquality_alt, 
voidElimination, 
sqequalRule, 
independent_pairFormation, 
universeIsType, 
productElimination, 
equalityTransitivity, 
equalitySymmetry, 
functionIsTypeImplies, 
inhabitedIsType, 
dependent_set_memberEquality_alt, 
because_Cache, 
addEquality, 
minusEquality, 
applyEquality, 
imageElimination, 
imageMemberEquality, 
baseClosed, 
productIsType, 
multiplyEquality, 
dependent_set_memberFormation_alt, 
unionElimination, 
closedConclusion, 
inrFormation_alt, 
functionIsType, 
equalityIstype, 
setIsType, 
instantiate, 
functionEquality, 
productEquality, 
intEquality, 
inlFormation_alt
Latex:
\mforall{}x:\mBbbR{}.  (rcos(x)  =  r1  \mLeftarrow{}{}\mRightarrow{}  \mexists{}n:\mBbbZ{}.  (x  =  2  *  n  *  \mpi{}))
Date html generated:
2019_10_31-AM-06_06_39
Last ObjectModification:
2019_05_17-PM-03_51_07
Theory : reals_2
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