5. Limit Diagonal Quantifiers
On the infinite ordered set {1,2,3…}, define the cofinity and infinity quantifiers thus:
Cof(n)(P(n)) = P
eventually stays true
= P is true for all but finitely many n
=
Exists(N)All(n) ( n>N implies P(n) )
= ( P(1) and P(2) and P(3) and P(4) and ... )
or (P(2) and P(3) and P(4) and ...)
or (P(3) and P(4) and ...)
or (P(4) and ... )
or ....
Inf(n)(P(n)) = P
keeps returning to true
= P is true for infinitely many n
= All(N)Exists(n)
( n>N and P(n) )
= ( P(1) or P(2) or P(3) or P(4) or ... )
and (P(2) or P(3) or P(4) or ...)
and (P(3) or P(4) or ... )
and (P(4) or ... )
and ....
Cof and Inf have these identities:
Not Cof(x)(P(x))
= Inf(x)(not P(x))
Not Inf(x)(P(x))
= Cof(x)(not P(x))
A and Cof(x)(P(x))
= Cof(x)(A and P(x))
A or Cof(x)(P(x))
= Cof(x)(A or P(x))
A and Inf(x)(P(x))
= Inf(x)(A and P(x))
A or Inf(x)(P(x))
= Inf(x)(A or P(x))
Here are definitions of the convergence and divergence
quantifiers:
Conv(n)(P(n)) = P is convergent
= Cof(n)(P(n)) or
Cof(n)(not P(n))
= Exists(N)All(m,n)
((m>N and n>N) implies (P(m) iff P(n) )
= P is
eventually constant
Div(n)(P(n)) = P is divergent
= Inf(n)(P(n)) and
Inf(n)(not P(n))
= All(N)Exists(m,n)
(m>N and n>N and (P(m) xor P(n))
= P is
persistently variable
These equations apply:
Cof(n)(P(n)) = Conv(n)(P(n)) and Inf(n)(P(n))
Cofinite equals convergent and persistent.
Inf(n)(P(n)) = Div(n)(P(n)) or Cof(n)(P(n))
Persistent equals divergent or cofinite.
Not Conv(P) = Div(P)
Conv(Not P) = Conv(P)
Not
Div(P) = Conv(P)
Div(Not P) = Div(P)
Partial
Distribution:
A and
Div(x)(P(x)) = Div(x)( A and P(x) )
A or Conv(x)(P(x))
= Conv(x)( A or P(x) )
“And” distributes over divergence, and “or” distributes
over convergence; but “and” does not distribute over convergence; nor does “or”
distribute over divergence:
T or Div(P(x)) = T; but Div(T or P(x)) = F.
F and Conv(P(x)) = F; but
Conv(F and P(x)) = T.
Divergence and convergence have these Equivalence Rules:
Conv(x)( P(x) iff Q(x) ) and
Conv(x)(Q(x) iff R(x))
Implies Conv(x)(P(x)
iff R(x))
If “P
iff Q” and “Q iff R” converge, then so does “P iff R”.
Conv(x)( P(x) iff Q(x) ) and
Conv(x)(Q(x))
Implies Conv(x)(P(x))
If “P
iff Q” and “Q” converge, then so does “P”.
Div(x)(P(x))
and Conv(x)(Q(x))
Implies
Div(x)(P(x) iff Q(x))
If “P” diverges and “Q” converges, then “P iff Q” diverges.
Conv(x)( P(x) iff Q(x) )
Implies Conv(x)(P(x)) iff
Conv(x)(Q(x))
If “P iff Q” converges, then “P” and “Q” are equally
convergent.
Div(x)(P(x))
xor Div(x)(Q(x))
implies
Div(x)( P(x) xor Q(x) )
If “P”
diverges or else “Q” diverges, then “P or else Q” diverges.
Convergence and divergence have two Continuity Rules:
If F(p1,
p2,… pn) is any function on Boolean logic, then
Conv(x)(P1(x)) and Conv(x)(P2(x)) and … Conv(x)(Pn(x))
Implies Conv(x)
( F(P1(x), P2(x), … Pn(x))
Convergent inputs imply a convergent output.
If F(p1,
p2,… pn) is any function on Boolean logic, then
Div(x) (
F(P1(x), P2(x), … Pn(x) )
Implies
Div(x)(P1(x)) or
Div(x)(P2(x)) or … Div(x)(Pn(x))
Divergent output implies a divergent input.