Nuprl Lemma : absval_mul
∀[x,y:ℤ].  (|x * y| = (|x| * |y|) ∈ ℤ)
Proof
Definitions occuring in Statement : 
absval: |i|, 
uall: ∀[x:A]. B[x], 
multiply: n * m, 
int: ℤ, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
uimplies: b supposing a, 
less_than: a < b, 
less_than': less_than'(a;b), 
top: Top, 
true: True, 
squash: ↓T, 
not: ¬A, 
false: False, 
bfalse: ff, 
exists: ∃x:A. B[x], 
subtype_rel: A ⊆r B, 
or: P ∨ Q, 
sq_type: SQType(T), 
guard: {T}, 
bnot: ¬bb, 
ifthenelse: if b then t else f fi , 
assert: ↑b, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
prop: ℙ, 
le: A ≤ B, 
nat: ℕ, 
subtract: n - m, 
nat_plus: ℕ+, 
decidable: Dec(P), 
cand: A c∧ B
Lemmas referenced : 
absval_unfold2, 
lt_int_wf, 
eqtt_to_assert, 
assert_of_lt_int, 
istype-top, 
istype-void, 
eqff_to_assert, 
int_subtype_base, 
bool_subtype_base, 
bool_cases_sqequal, 
subtype_base_sq, 
iff_transitivity, 
assert_wf, 
bnot_wf, 
not_wf, 
less_than_wf, 
iff_weakening_uiff, 
assert_of_bnot, 
istype-less_than, 
istype-assert, 
not-lt-2, 
minus-one-mul, 
mul-associates, 
istype-int, 
minus-one-mul-top, 
mul-swap, 
one-mul, 
bool_wf, 
less_than_irreflexivity, 
less_than_transitivity1, 
le_wf, 
le_weakening2, 
mul_preserves_le, 
mul-commutes, 
zero-mul, 
le-add-cancel, 
zero-add, 
add-associates, 
add_functionality_wrt_le, 
add-commutes, 
add-zero, 
minus-zero, 
minus-add, 
condition-implies-le, 
less-iff-le, 
mul_preserves_lt, 
decidable__int_equal, 
decidable__lt, 
istype-false, 
not-equal-2, 
add_functionality_wrt_lt, 
le_reflexive, 
add-mul-special
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
sqequalRule, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
multiplyEquality, 
hypothesisEquality, 
hypothesis, 
natural_numberEquality, 
Error :inhabitedIsType, 
Error :lambdaFormation_alt, 
unionElimination, 
equalityElimination, 
equalityTransitivity, 
equalitySymmetry, 
productElimination, 
independent_isectElimination, 
because_Cache, 
lessCases, 
axiomSqEquality, 
Error :isect_memberEquality_alt, 
Error :isectIsTypeImplies, 
independent_pairFormation, 
voidElimination, 
imageMemberEquality, 
baseClosed, 
imageElimination, 
independent_functionElimination, 
Error :dependent_pairFormation_alt, 
Error :equalityIsType4, 
baseApply, 
closedConclusion, 
applyEquality, 
promote_hyp, 
dependent_functionElimination, 
instantiate, 
Error :functionIsType, 
Error :universeIsType, 
Error :equalityIsType1, 
minusEquality, 
Error :lambdaEquality_alt, 
cumulativity, 
axiomEquality, 
voidEquality, 
isect_memberEquality, 
dependent_set_memberEquality, 
intEquality, 
lambdaEquality, 
addEquality
Latex:
\mforall{}[x,y:\mBbbZ{}].    (|x  *  y|  =  (|x|  *  |y|))
Date html generated:
2019_06_20-AM-11_24_38
Last ObjectModification:
2018_10_27-AM-11_38_11
Theory : arithmetic
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