> I'm not sure I see your point here; indeed, an ideal of ring with a > multiplicative unit need not necessarily include the unit, but this > doesn't make it less of a ring.
Yes it does. It makes it not a ring at all. A ring is a set with two binary operations, + and *, *with the properties* that it is a group under each operation (is associative, closed, contains the identity), is commutative under +, and has the distributive property (some definitions also require that 1 != 0, though I personally find this to be unnecessary). If it lacks any of these properties, it is not a ring. Saying something like "a ring with a multiplicative unit" is meaningless. Every ring has a multiplicative unit, by definition. Aaron Meurer -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
