DirectProduct has CancellationAbelianMonoid, if its second argument has it.
But call of subtractIfCan seemingly gives an infinite loop, if the
second argument is NNI, it works for INT:
Does anyone see what is going on here?
Regards
Johannes Grabmeier
(1) -> )read testPRDP
E := DirectProduct(6, INT)
(1) DirectProduct(6,Integer)
Type: Type
b1 : E := unitVector 1
(2) [1,0,0,0,0,0]
Type: DirectProduct(6,Integer)
E has AbelianGroup
(3) true
Type: Boolean
b1-b1
(4) [0,0,0,0,0,0]
Type: DirectProduct(6,Integer)
E' := DirectProduct(6, NNI)
(5) DirectProduct(6,NonNegativeInteger)
Type: Type
E' has AbelianGroup
(6) false
Type: Boolean
E' has CancellationAbelianMonoid
(7) true
Type: Boolean
a1 : E' := unitVector 1
(8) [1,0,0,0,0,0]
Type:
DirectProduct(6,NonNegativeInteger)
subtractIfCan(a1,a1)
INFO: Control stack guard page reprotected
INFO: Control stack guard page unprotected
Control stack guard page temporarily disabled: proceed with caution
>> System error:
Control stack exhausted (no more space for function call frames).
This is probably due to heavily nested or infinitely recursive function
calls, or a tail call that SBCL cannot or has not optimized away.
PROCEED WITH CAUTION.
(9) -> a1-a1
INFO: Control stack guard page reprotected
INFO: Control stack guard page unprotected
Control stack guard page temporarily disabled: proceed with caution
>> System error:
Control stack exhausted (no more space for function call frames).
This is probably due to heavily nested or infinitely recursive function
calls, or a tail call that SBCL cannot or has not optimized away.
PROCEED WITH CAUTION.
--
Mit freundlichen Grüßen
Johannes Grabmeier
Prof. Dr. Johannes Grabmeier
Köckstraße 1, D-94469 Deggendorf
Tel. +49-(0)-991-2979584, Tel. +49-(0)-151-681-70756
Tel. +49-(0)-991-3615-141 (d), Fax: +49-(0)-32224-192688
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