For a module over a commutative ring presented by a matrix with n generators, its zeroth Fitting ideal is generated by all n-by-n minors of the relation matrix. It is independent of the chosen finite presentation. Over a unique factorization domain, the greatest common divisor of these minors defines the module order up to a unit. This does not require a Smith normal form over the ring. The square Seifert-matrix presentation of the Alexander module makes the order its determinant.
// Target: knot-theory.bigb
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In the context of algebraic geometry and commutative algebra, a **fitting ideal** is a specific type of ideal associated with a module over a ring. It captures information about the relations between elements of the module. For a finitely generated module \(M\) over a Noetherian ring \(R\), the Fitting ideals provide a way of understanding the structure of \(M\) in terms of its generators and relations.