Symbolic method (combinatorics): Difference between revisions

Revision as of 09:30, 11 October 2018

Revision as of 23:19, 31 July 2019

Line 284:

A class of combinatorial structures is said to be ''constructible'' or ''specifiable'' when it admits a specification.

For example, the set of trees whose leaves's depth is even (respectively, odd) can be defined using the specification with two classes <math>\mathcal A_{even}</math> and <math>\mathcal A_{odd}</math>. Those clasessclasses should satisfy the equation <math>\mathcal A_{odd}=\mathcal Z\times \mathrm{Seq}_{\ge1}\mathcal A_{even}</math> and <math>\mathcal A_{even}=\mathcal Z\times \mathrm{Seq}\mathcal A_{odd}</math>.

==Labelled structures==