primitive recursive predicate
primitive recursive predicates are primitive recursive functions whose range is
, 0 and 1 being substitutes for true and false.
[cite:;taken from @computability_davis_1994 chapter 3.5 primitive recursive functions]
[cite:;taken from @computability_davis_1994 chapter 3.5 primitive recursive functions]
the function
is defined as

is primitive recursive since
or we can simply write the recursion equations:
[cite:;taken from @computability_davis_1994 chapter 3.5 primitive recursive functions]
the predicate is defined as 1 if the values of
and
are the same and 0 otherwise. thus we wish to show that the function
is primitive recursive. this follows immediately from the equation
[cite:;taken from @computability_davis_1994 chapter 3.5 primitive recursive functions]
this predicate is simply the primitive recursive function
.
[cite:;taken from @computability_davis_1994 chapter 3.5 primitive recursive functions]
[cite:;taken from @computability_davis_1994 chapter 3.5 primitive recursive functions]
let
be a PRC class. if
are predicates that belong to
, then so are
, and
.
[cite:;taken from @computability_davis_1994 theorem 5.1]
[cite:;taken from @computability_davis_1994 theorem 5.1]
we can write
or more simply
[cite:;taken from @computability_davis_1994 chapter 3.5 primitive recursive functions]
let
be a PRC class. let the functions
and the predicate
belong to
. let
then
belongs to
.
[cite:;taken from @computability_davis_1994 theorem 5.4]
[cite:;taken from @computability_davis_1994 theorem 5.4]
let
be a PRC class, let
-ary functions
and predicates
belong to
, and let
for all
and all
. if
then
also belongs to
.
[cite:;taken from @computability_davis_1994 corollary 5.5]
[cite:;taken from @computability_davis_1994 corollary 5.5]
if the predicate
belongs to some PRC class
, then so do the predicates
this is directly related to unbounded_search_operator.html.
[cite:;taken from @computability_davis_1994 theorem 6.3]
[cite:;taken from @computability_davis_1994 theorem 6.3]
the predicate is primitive recursive since
the predicate "
is a prime" is primitive recursive since
(a number is a prime if it is greater than 1 and it has no divisors other than 1 and itself.)
[cite:;taken from @computability_davis_1994 chapter 3.6 iterated operations and bounded quantifiers]
[cite:;taken from @computability_davis_1994 chapter 3.6 iterated operations and bounded quantifiers]