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ExpandAll[(a + b) ** c] ?

• To: mathgroup at smc.vnet.net
• Subject: [mg71097] ExpandAll[(a + b) ** c] ?
• From: "Christoph Lhotka" <lhotka at astro.univie.ac.at>
• Date: Wed, 8 Nov 2006 06:15:19 -0500 (EST)

Hello Mathgroup!

Ho do I make the non-commutative operator ** distributiv with respect to +,
thus the expression "ExpandAll[(a + b) ** c]" evaluates to "a**c + b**c", by
setting appropiate attributes to ** and + ? 

PS: Sure, the rule (a+b)**c->a**c+b**c after the expression works fine, but
its a rule, not an attribute to **, nor to +.

Discussion point: Is there a any reason, why the non-commutative but
associative opertor ** should not be distributive with respect to a linear
operator + in general? To my opinion this would be more straightforward, when
calling the operator a multiplicative one. What do you think?

Thank you
Christoph 

• Follow-Ups:
  • Re: ExpandAll[(a + b) ** c] ?
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>