@ARTICLE {,
title = {Matematické nástroje},
author = {Vrábel, Peter},
journal = {Obzory matematiky, fyziky a informatiky},
year = {2009},
volume = {38},
number = {2},
pages = {11--15},
issn = {1335-4981},
abstract = {A semi-invariant is the quantity which is changed monotonically and gains only finite values. Semi-invariants are often used in the analysis of evolving systems to show that certain final configurations must occur. Every investigated object of a problem is assigned some value of quantity and is defined a suitable operation on the set of objects. We concentrate on the least"or the greatest value of semi-invariant and we the problem solve by its means.},
}