Editing Combinatorial class (section)

In [[mathematics]], a '''combinatorial class''' is a [[countable set]] of mathematical objects, together with a size function mapping each object to a non-negative integer, such that there are finitely many objects of each size.<ref>{{citation
 | last1 = Martínez | first1 = Conrado
 | last2 = Molinero | first2 = Xavier
 | doi = 10.1002/rsa.10025
 | issue = 3–4
 | journal = Random Structures & Algorithms
 | mr = 1871563
 | pages = 472–497
 | title = A generic approach for the unranking of labeled combinatorial classes
 | volume = 19
 | year = 2001| url = http://www.lsi.upc.edu/~conrado/research/papers/rsa-mm01.pdf
 }}.</ref><ref>{{citation
 | last1 = Duchon | first1 = Philippe
 | last2 = Flajolet | first2 = Philippe | authorlink = Philippe Flajolet
 | last3 = Louchard | first3 = Guy
 | last4 = Schaeffer | first4 = Gilles
 | doi = 10.1017/S0963548304006315
 | issue = 4–5
 | journal = [[Combinatorics, Probability and Computing]]
 | mr = 2095975
 | pages = 577–625
 | title = Boltzmann samplers for the random generation of combinatorial structures
 | volume = 13
 | year = 2004}}.</ref>