See also NonNegativeInteger

)abbrev domain PI PositiveInteger
++ Author:
++ Date Created:
++ Change History:
++ Basic Operations:
++ Related Constructors:
++ Keywords: positive integer
++ Description: \spadtype{PositiveInteger} provides functions for
++   positive integers.
PositiveInteger: Join(AbelianSemiGroup,OrderedSet,Monoid) with
            gcd: (%,%) -> %
              ++ gcd(a,b) computes the greatest common divisor of two
              ++ positive integers \spad{a} and b.
            commutative("*")
              ++ commutative("*") means multiplication is commutative : x*y = y*x
 == SubDomain(NonNegativeInteger,x+->(x > 0)) add
   x:%
   y:%

   Compiling FriCAS source code from file 
      /var/zope2/var/LatexWiki/408887470856718679-25px001.spad using 
      old system compiler.
   PI abbreviates domain PositiveInteger 
------------------------------------------------------------------------
   initializing NRLIB PI for PositiveInteger 
   compiling into NRLIB PI 
****** comp fails at level 1 with expression: ******
((+-> |x| (< 0 |x|)))
****** level 1  ******
$x:= (+-> x (< (Zero) x))
$m:= (Boolean)
$f:=
((((|#1| #) (* #) (+ #) (< #) ...)))

   >> Apparent user error:
   compLambda: signature needed
   (+-> x (< (Zero) x))

)show PositiveInteger

 PositiveInteger  is a domain constructor
 Abbreviation for PositiveInteger is PI
 This constructor is exposed in this frame.
------------------------------- Operations --------------------------------
 ?*? : (%,%) -> %                      ?*? : (PositiveInteger,%) -> %
 ?+? : (%,%) -> %                      ?<? : (%,%) -> Boolean
 ?<=? : (%,%) -> Boolean               ?=? : (%,%) -> Boolean
 ?>? : (%,%) -> Boolean                ?>=? : (%,%) -> Boolean
 1 : () -> %                           ?^? : (%,PositiveInteger) -> %
 coerce : % -> OutputForm              gcd : (%,%) -> %
 hash : % -> SingleInteger             latex : % -> String
 max : (%,%) -> %                      min : (%,%) -> %
 one? : % -> Boolean                   recip : % -> Union(%,"failed")
 sample : () -> %                      smaller? : (%,%) -> Boolean
 ?~=? : (%,%) -> Boolean
 ?^? : (%,NonNegativeInteger) -> %