User mathfor - MathOverflow most recent 30 from http://mathoverflow.net 2013-06-19T21:45:45Z http://mathoverflow.net/feeds/user/3539 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/12956/terminology-name-for-a-homomorphism-from-the-free-object Terminology: Name for a homomorphism from the free object? mathfor 2010-01-25T19:20:21Z 2010-01-25T20:40:33Z <p>Is there a standard name for taking a homomorphism from the free object over an algebraic structure? Roughly speaking, this should amount to <em>evaluation</em> of any element of the free object under the homomorphism.</p> <p>For example, take the free commutative monoid over the set of natural numbers; elements of this monoid are finite multisets of natural numbers. By taking commutative monoid homomorphisms we can express many common operations, such as cardinality (map every generator to 1 and take sum as the monoid operation), sum (take every generator to itself and map the monoid operation to sum of natural numbers), product (take product of natural numbers rather than sum) etc.</p> <p>Since these operations are all abelian monoid operations, we can expect a sensible result which will not depend on our multiset being non-empty or listing its elements in a specific order.</p> <p>Does this idea generalize to other algebraic structures? Any known references?</p>