Nuprl Lemma : gcd-mod
∀x:ℕ+. ∀y:ℕ.  (gcd(x;y mod x) = gcd(x;y) ∈ ℤ)
Proof
Definitions occuring in Statement : 
modulus: a mod n, 
gcd: gcd(a;b), 
nat_plus: ℕ+, 
nat: ℕ, 
all: ∀x:A. B[x], 
int: ℤ, 
equal: s = t ∈ T
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
member: t ∈ T, 
nat: ℕ, 
decidable: Dec(P), 
or: P ∨ Q, 
uall: ∀[x:A]. B[x], 
uimplies: b supposing a, 
sq_type: SQType(T), 
implies: P ⇒ Q, 
guard: {T}, 
squash: ↓T, 
prop: ℙ, 
nat_plus: ℕ+, 
int_seg: {i..j-}, 
lelt: i ≤ j < k, 
and: P ∧ Q, 
le: A ≤ B, 
less_than': less_than'(a;b), 
false: False, 
not: ¬A, 
ge: i ≥ j , 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
top: Top, 
true: True, 
subtype_rel: A ⊆r B, 
iff: P ⇐⇒ Q, 
int_nzero: ℤ-o, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
nequal: a ≠ b ∈ T , 
gcd: gcd(a;b), 
int_upper: {i...}, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
uiff: uiff(P;Q), 
ifthenelse: if b then t else f fi , 
bfalse: ff, 
bnot: ¬bb, 
assert: ↑b
Lemmas referenced : 
decidable__equal_int, 
subtype_base_sq, 
int_subtype_base, 
nat_wf, 
nat_plus_wf, 
gcd_wf, 
squash_wf, 
true_wf, 
modulus_base, 
false_wf, 
nat_properties, 
nat_plus_properties, 
decidable__lt, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformnot_wf, 
intformless_wf, 
itermConstant_wf, 
itermVar_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_less_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_wf, 
lelt_wf, 
equal_wf, 
iff_weakening_equal, 
modulus-is-rem, 
subtype_rel_sets, 
less_than_wf, 
nequal_wf, 
intformeq_wf, 
int_formula_prop_eq_lemma, 
equal-wf-base, 
gcd_com, 
nat_plus_subtype_nat, 
int_upper_subtype_nat, 
le_wf, 
nequal-le-implies, 
zero-add, 
eq_int_wf, 
bool_wf, 
eqtt_to_assert, 
assert_of_eq_int, 
int_upper_properties, 
eqff_to_assert, 
bool_cases_sqequal, 
bool_subtype_base, 
assert-bnot, 
neg_assert_of_eq_int
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
dependent_functionElimination, 
thin, 
setElimination, 
rename, 
hypothesisEquality, 
hypothesis, 
natural_numberEquality, 
unionElimination, 
instantiate, 
isectElimination, 
cumulativity, 
intEquality, 
independent_isectElimination, 
because_Cache, 
independent_functionElimination, 
applyEquality, 
lambdaEquality, 
imageElimination, 
equalityTransitivity, 
equalitySymmetry, 
sqequalRule, 
dependent_set_memberEquality, 
independent_pairFormation, 
dependent_pairFormation, 
int_eqEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
computeAll, 
universeEquality, 
imageMemberEquality, 
baseClosed, 
productElimination, 
setEquality, 
applyLambdaEquality, 
hypothesis_subsumption, 
equalityElimination, 
promote_hyp, 
remainderEquality
Latex:
\mforall{}x:\mBbbN{}\msupplus{}.  \mforall{}y:\mBbbN{}.    (gcd(x;y  mod  x)  =  gcd(x;y))
Date html generated:
2018_05_21-PM-08_57_29
Last ObjectModification:
2017_07_26-PM-06_21_15
Theory : general
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