diff options
Diffstat (limited to 'src/algebra/catdef.spad.pamphlet')
| -rw-r--r-- | src/algebra/catdef.spad.pamphlet | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/src/algebra/catdef.spad.pamphlet b/src/algebra/catdef.spad.pamphlet index 1e9370df..ee556b91 100644 --- a/src/algebra/catdef.spad.pamphlet +++ b/src/algebra/catdef.spad.pamphlet @@ -240,7 +240,7 @@ AbelianGroup(): Category == Join(CancellationAbelianMonoid, LeftLinearSet Intege ++ and \spad{y} i.e. \spad{x + (-y)}. add (x:% - y:%):% == x+(-y) - subtractIfCan(x:%, y:%):Union(%, "failed") == (x-y) :: Union(%,"failed") + subtractIfCan(x:%, y:%) == just(x-y) n:NonNegativeInteger * x:% == (n::Integer) * x import RepeatedDoubling(%) if not (% has Ring) then @@ -514,9 +514,9 @@ BiModule(R:Ring,S:Ring):Category == ++ \spad{c = a+b <=> c-b = a} CancellationAbelianMonoid(): Category == AbelianMonoid with --operations - subtractIfCan: (%,%) -> Union(%,"failed") + subtractIfCan: (%,%) -> Maybe % ++ subtractIfCan(x, y) returns an element z such that \spad{z+y=x} - ++ or "failed" if no such element exists. + ++ or \spad{nothing} if no such element exists. @ |