Restrictions for a molecular formula

Restricting the number of atoms We can enter an interval of natural numbers that restricts the number of atoms occuring in the molecule. 

Restricting the number of heteroatoms The user can enter an interval that restricts the total number of heteroatoms. 

Even if these restrictions are not finite (i.e. an interval of the form [a, oo[ occurs, consisting of the natural numbers i a), their combination may lead to a finite set of candidates. In MOLGEN-MS an additional restriction is implemented. 

These restrictions influence the presence of elements in the molecular formula, while 

Relaxing connectedness Disconnected molecular graphs may or may not be allowed. The implementation applies that the degree partition of a simple graph is the degree partition of a connected simple graph if and only if B(y) n - 1 (see the items following Remark 2.35). 

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