Constructions and properties of the new combinatorial schemes
Xiaonan Li, LI Sheng-gang · Journal of Shandong University · 2006
The necessary and sufficient condition is given to ensure the restriction and contraction to the same subset of a poset matroid processes the same result,which indicates that the rank function plays an important role in the study of poset matroids.And then some operations on combinatorial schemes are discussed, such as restriction,contraction,truncation and elongation.Some properties of these operations are also studied.