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-rw-r--r--src/algebra/product.spad.pamphlet8
1 files changed, 4 insertions, 4 deletions
diff --git a/src/algebra/product.spad.pamphlet b/src/algebra/product.spad.pamphlet
index e10d11a8..94635e44 100644
--- a/src/algebra/product.spad.pamphlet
+++ b/src/algebra/product.spad.pamphlet
@@ -80,10 +80,10 @@ Product (A:SetCategory,B:SetCategory) : C == T
if A has CancellationAbelianMonoid and
B has CancellationAbelianMonoid then
- subtractIfCan(x, y) : Union(%,"failed") ==
- (na:= subtractIfCan(x.acomp, y.acomp)) case "failed" => "failed"
- (nb:= subtractIfCan(x.bcomp, y.bcomp)) case "failed" => "failed"
- [na::A,nb::B]
+ subtractIfCan(x, y) ==
+ (na:= subtractIfCan(x.acomp, y.acomp)) case nothing => nothing
+ (nb:= subtractIfCan(x.bcomp, y.bcomp)) case nothing => nothing
+ just [na::A,nb::B]
if A has AbelianGroup and B has AbelianGroup then
- x == [- x.acomp,-x.bcomp]