Nuprl Lemma : subtract_nat_wf
∀[i,j:ℤ].  i - j ∈ ℕ supposing j ≤ i
Proof
Definitions occuring in Statement : 
nat: ℕ
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
le: A ≤ B
, 
member: t ∈ T
, 
subtract: n - m
, 
int: ℤ
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uimplies: b supposing a
, 
nat: ℕ
, 
le: A ≤ B
, 
and: P ∧ Q
, 
subtract: n - m
, 
prop: ℙ
, 
all: ∀x:A. B[x]
, 
subtype_rel: A ⊆r B
, 
top: Top
, 
uiff: uiff(P;Q)
, 
nat_plus: ℕ+
, 
less_than: a < b
, 
squash: ↓T
, 
less_than': less_than'(a;b)
, 
true: True
, 
implies: P 
⇒ Q
, 
not: ¬A
, 
false: False
, 
decidable: Dec(P)
, 
or: P ∨ Q
Lemmas referenced : 
subtract_wf, 
minus-one-mul, 
le_wf, 
istype-int, 
add_functionality_wrt_le, 
le_reflexive, 
minus-one-mul-top, 
istype-void, 
one-mul, 
add-swap, 
add-commutes, 
add-associates, 
add-mul-special, 
two-mul, 
mul-distributes-right, 
zero-mul, 
zero-add, 
not-le-2, 
minus-zero, 
add-zero, 
omega-shadow, 
less_than_wf, 
mul-distributes, 
mul-associates, 
mul-commutes, 
le-add-cancel-alt, 
decidable__le
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
Error :dependent_set_memberEquality_alt, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
productElimination, 
sqequalRule, 
Error :universeIsType, 
natural_numberEquality, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
Error :isect_memberEquality_alt, 
because_Cache, 
Error :inhabitedIsType, 
multiplyEquality, 
independent_isectElimination, 
dependent_functionElimination, 
applyEquality, 
Error :lambdaEquality_alt, 
voidElimination, 
addEquality, 
minusEquality, 
independent_pairFormation, 
imageMemberEquality, 
baseClosed, 
independent_functionElimination, 
unionElimination
Latex:
\mforall{}[i,j:\mBbbZ{}].    i  -  j  \mmember{}  \mBbbN{}  supposing  j  \mleq{}  i
Date html generated:
2019_06_20-AM-11_26_25
Last ObjectModification:
2018_10_03-AM-10_13_23
Theory : arithmetic
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