Nuprl Lemma : gcd_wf
∀a,b:ℤ.  (gcd(a;b) ∈ ℤ)
Proof
Definitions occuring in Statement : 
gcd: gcd(a;b), 
all: ∀x:A. B[x], 
member: t ∈ T, 
int: ℤ
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
nat: ℕ, 
implies: P ⇒ Q, 
false: False, 
ge: i ≥ j , 
guard: {T}, 
uimplies: b supposing a, 
prop: ℙ, 
subtype_rel: A ⊆r B, 
le: A ≤ B, 
and: P ∧ Q, 
decidable: Dec(P), 
or: P ∨ Q, 
iff: P ⇐⇒ Q, 
not: ¬A, 
rev_implies: P ⇐ Q, 
uiff: uiff(P;Q), 
subtract: n - m, 
top: Top, 
less_than': less_than'(a;b), 
true: True, 
gcd: gcd(a;b), 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
ifthenelse: if b then t else f fi , 
bfalse: ff, 
exists: ∃x:A. B[x], 
sq_type: SQType(T), 
bnot: ¬bb, 
assert: ↑b, 
nequal: a ≠ b ∈ T , 
int_nzero: ℤ-o
Lemmas referenced : 
nat_properties, 
less_than_transitivity1, 
less_than_irreflexivity, 
ge_wf, 
less_than_wf, 
absval_wf, 
nat_wf, 
absval-non-neg, 
decidable__le, 
subtract_wf, 
false_wf, 
not-ge-2, 
less-iff-le, 
condition-implies-le, 
minus-one-mul, 
zero-add, 
minus-one-mul-top, 
minus-add, 
minus-minus, 
add-associates, 
add-swap, 
add-commutes, 
add_functionality_wrt_le, 
add-zero, 
le-add-cancel, 
eq_int_wf, 
bool_wf, 
eqtt_to_assert, 
assert_of_eq_int, 
eqff_to_assert, 
equal_wf, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
iff_transitivity, 
assert_wf, 
bnot_wf, 
not_wf, 
equal-wf-base, 
int_subtype_base, 
iff_weakening_uiff, 
assert_of_bnot, 
rem_bounds_z, 
nequal_wf, 
decidable__lt, 
not-lt-2, 
not-le-2, 
le_wf, 
add-mul-special, 
zero-mul
Rules used in proof : 
cut, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
setElimination, 
rename, 
sqequalRule, 
intWeakElimination, 
natural_numberEquality, 
independent_isectElimination, 
independent_functionElimination, 
voidElimination, 
lambdaEquality, 
dependent_functionElimination, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
applyEquality, 
intEquality, 
productElimination, 
because_Cache, 
unionElimination, 
independent_pairFormation, 
addEquality, 
isect_memberEquality, 
voidEquality, 
minusEquality, 
equalityElimination, 
dependent_pairFormation, 
promote_hyp, 
instantiate, 
cumulativity, 
baseClosed, 
impliesFunctionality, 
remainderEquality, 
dependent_set_memberEquality, 
multiplyEquality
Latex:
\mforall{}a,b:\mBbbZ{}.    (gcd(a;b)  \mmember{}  \mBbbZ{})
Date html generated:
2017_04_14-AM-07_18_48
Last ObjectModification:
2017_02_27-PM-02_52_44
Theory : arithmetic
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