Nuprl Lemma : mod2-is-one
∀x:ℤ. ((x mod 2) = 1 ∈ ℤ ⇐⇒ ∃n:ℤ. (x = ((2 * n) + 1) ∈ ℤ))
Proof
Definitions occuring in Statement : 
modulus: a mod n, 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
iff: P ⇐⇒ Q, 
multiply: n * m, 
add: n + m, 
natural_number: $n, 
int: ℤ, 
equal: s = t ∈ T
Definitions unfolded in proof : 
so_apply: x[s], 
so_lambda: λ2x.t[x], 
decidable: Dec(P), 
exists: ∃x:A. B[x], 
bfalse: ff, 
btrue: tt, 
ifthenelse: if b then t else f fi , 
or: P ∨ Q, 
less_than': less_than'(a;b), 
le: A ≤ B, 
uiff: uiff(P;Q), 
top: Top, 
subtract: n - m, 
rev_implies: P ⇐ Q, 
and: P ∧ Q, 
iff: P ⇐⇒ Q, 
subtype_rel: A ⊆r B, 
prop: ℙ, 
false: False, 
guard: {T}, 
sq_type: SQType(T), 
uimplies: b supposing a, 
implies: P ⇒ Q, 
not: ¬A, 
nequal: a ≠ b ∈ T , 
true: True, 
int_nzero: ℤ-o, 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
all: ∀x:A. B[x]
Lemmas referenced : 
iff_wf, 
mod2-is-zero, 
exists_wf, 
minus-minus, 
mul-associates, 
minus-add, 
not-equal-2, 
false_wf, 
decidable__int_equal, 
assert_of_bnot, 
iff_weakening_uiff, 
iff_transitivity, 
eqff_to_assert, 
assert_of_eq_int, 
eqtt_to_assert, 
bool_subtype_base, 
bool_wf, 
bool_cases, 
le-add-cancel, 
add-zero, 
add_functionality_wrt_le, 
minus-one-mul-top, 
minus-one-mul, 
condition-implies-le, 
le_antisymmetry_iff, 
not_wf, 
bnot_wf, 
assert_wf, 
zero-add, 
add-commutes, 
add-swap, 
add-associates, 
nequal_wf, 
true_wf, 
equal-wf-base, 
int_subtype_base, 
subtype_base_sq, 
modulus_wf, 
eq_int_wf, 
subtract_wf, 
mod2-add1
Rules used in proof : 
promote_hyp, 
multiplyEquality, 
dependent_pairFormation, 
impliesFunctionality, 
unionElimination, 
productElimination, 
addEquality, 
minusEquality, 
voidEquality, 
isect_memberEquality, 
lambdaEquality, 
closedConclusion, 
baseApply, 
independent_pairFormation, 
sqequalRule, 
because_Cache, 
applyEquality, 
baseClosed, 
voidElimination, 
independent_functionElimination, 
equalitySymmetry, 
equalityTransitivity, 
independent_isectElimination, 
cumulativity, 
instantiate, 
addLevel, 
dependent_set_memberEquality, 
hypothesis, 
natural_numberEquality, 
hypothesisEquality, 
isectElimination, 
thin, 
dependent_functionElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
introduction, 
intEquality, 
cut, 
lambdaFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}x:\mBbbZ{}.  ((x  mod  2)  =  1  \mLeftarrow{}{}\mRightarrow{}  \mexists{}n:\mBbbZ{}.  (x  =  ((2  *  n)  +  1)))
Date html generated:
2018_07_25-PM-01_27_57
Last ObjectModification:
2018_06_27-PM-05_54_42
Theory : arithmetic
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