Nuprl Lemma : ndiff_ndiff
∀[a,b:ℤ]. ∀[c:ℕ].  (((a -- b) -- c) = (a -- (b + c)) ∈ ℤ)
Proof
Definitions occuring in Statement : 
ndiff: a -- b, 
nat: ℕ, 
uall: ∀[x:A]. B[x], 
add: n + m, 
int: ℤ, 
equal: s = t ∈ T
Definitions unfolded in proof : 
ndiff: a -- b, 
imax: imax(a;b), 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
uimplies: b supposing a, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
ifthenelse: if b then t else f fi , 
nat: ℕ, 
bfalse: ff, 
exists: ∃x:A. B[x], 
prop: ℙ, 
or: P ∨ Q, 
sq_type: SQType(T), 
guard: {T}, 
bnot: ¬bb, 
assert: ↑b, 
false: False, 
not: ¬A, 
le: A ≤ B, 
ge: i ≥ j , 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
top: Top, 
squash: ↓T, 
subtract: n - m, 
subtype_rel: A ⊆r B, 
true: True, 
has-value: (a)↓
Lemmas referenced : 
nat_wf, 
value-type-has-value, 
int-value-type, 
subtract_wf, 
le_int_wf, 
bool_wf, 
eqtt_to_assert, 
assert_of_le_int, 
eqff_to_assert, 
equal_wf, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
assert-bnot, 
le_wf, 
nat_properties, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformle_wf, 
itermSubtract_wf, 
itermConstant_wf, 
itermVar_wf, 
intformnot_wf, 
itermAdd_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_le_lemma, 
int_term_value_subtract_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_not_lemma, 
int_term_value_add_lemma, 
int_formula_prop_wf, 
ifthenelse_wf, 
squash_wf, 
true_wf, 
add-associates, 
minus-one-mul, 
minus-add, 
minus-one-mul-top
Rules used in proof : 
sqequalSubstitution, 
sqequalRule, 
sqequalReflexivity, 
sqequalTransitivity, 
computationStep, 
isect_memberFormation, 
introduction, 
cut, 
hypothesis, 
extract_by_obid, 
sqequalHypSubstitution, 
isect_memberEquality, 
isectElimination, 
thin, 
hypothesisEquality, 
axiomEquality, 
because_Cache, 
intEquality, 
independent_isectElimination, 
natural_numberEquality, 
lambdaFormation, 
unionElimination, 
equalityElimination, 
productElimination, 
setElimination, 
rename, 
dependent_pairFormation, 
equalityTransitivity, 
equalitySymmetry, 
promote_hyp, 
dependent_functionElimination, 
instantiate, 
cumulativity, 
independent_functionElimination, 
voidElimination, 
addEquality, 
lambdaEquality, 
int_eqEquality, 
voidEquality, 
independent_pairFormation, 
computeAll, 
applyEquality, 
imageElimination, 
universeEquality, 
minusEquality, 
imageMemberEquality, 
baseClosed, 
callbyvalueReduce
Latex:
\mforall{}[a,b:\mBbbZ{}].  \mforall{}[c:\mBbbN{}].    (((a  --  b)  --  c)  =  (a  --  (b  +  c)))
Date html generated:
2017_04_14-AM-09_14_58
Last ObjectModification:
2017_02_27-PM-03_52_56
Theory : int_2
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