Enumeration of minimal 3D polyominoes inscribed in a rectangular prism

We consider the family of 3D minimal polyominoes inscribed in a rectanglar prism. These objects are polyominos and so they are connected sets of unitary cubic cells inscribed in a given rectangular prism of size $b\times k \times h$ and of minimal volume equal to $b+k+h-2$. They extend the concept of minimal 2D polyominoes inscribed in a rectangle studied in a previous work. Using their geometric structure and elementary combinatorial principles, we construct rational generating functions of minimal 3D polyominoes. We also obtain a number of exact formulas and recurrences for sub-families of these polyominoes

A family of classes in nested chain abacus and related generating functions

Abacus model has been employed widely to represent partitions for any positive integer. However, no study has been carried out to develop connected beads of abacus in graphical representation for discrete objects. To resolve this connectedness problem this study is oriented in characterising n - connected objects knows as n connected ominoes, which then generate nested chain abacus. Furthermore, the theoretical conceptual properties for the nested chain abacus are being formulated. Along the construction, three different types of transformation are being created that are essential in building a family of classes. To enhance further, based on theses classes, generating functions are also being formulated by employing enumeration of combinatorial objects (ECO). In ECO method, each object is obtained from smaller object by making some local expansions. These local expansions are described in a simple way by a succession rule which can be translated into a function equation for the generating function. In summary, this stud has succeeded in producing novel graphical representation of nested chain abacus, which can be applied in tiling finite grid

Extremal Polyominoes

Název práce: Extremal Polyominoes Autor: Veronika Steffanová Katedra: Katedra aplikované matematiky Vedoucí diplomové práce: Doc. RNDr. Pavel Valtr, Dr. Abstrakt: Práce se zabývá tématem polymin a dalších rovinných obrazců, které se skládají z pravidelných mnohoúhelníků, konkrétně polyiamondů a polyhexů. Zaměřili jsme se na základní geometrické vlastnosti: obvod, kon- vexní obal a ohraničující čtverec/šestiúhelník. Tyto parametry minimal- izujeme nebo maximalizujeme pro pevně danou velikost polymina, kterou značíme jako n. Vzhledem k n odvozujeme vzorec pro maximální a minimální hodnoty zvoleného parametru a také se snažíme vyjmenovat všechna polymina, která tohoto maxima dosahují. Některé problémy už byly vyřešeny dříve jinými autory a my přinášíme shrnutí jejich výsledků. Jiné jsme vyřešili my, jmenovitě problém maximálního ohraničujícího čtverce/šestiúhelníku a maximálního konvexního obalu pro polyiamondy. Některé otázky zůstávají i nadále otevřeny a my nabízíme alespoň pozorování, která mohou posloužit v dalším výzkumu. Klíčová slova: Polymino, konvexní obal, extremální otázky, rovina 1Title: Extremal Polyominoes Author: Veronika Steffanová Department: Department of Applied Mathematics Supervisor: Doc. RNDr. Pavel Valtr, Dr. Abstract: The thesis is focused on polyominoes and other planar figures consisting of regular polygons, namely polyiamonds and polyhexes. We study the basic geometrical properties: the perimeter, the convex hull and the bounding rectangle/hexagon. We maximise and minimise these parameters and for the fixed size of the polyomino, denoted by n. We compute the extremal values of a chosen parameter and then we try to enumerate all polyominoes of the size n, which has the extremal property. Some of the problems were solved by other authors. We summarise their results. Some of the problems were solved by us, namely the maximal bounding rectan- gle/hexagon and maximal convex hull of polyiamonds. There are still sev- eral topics which remain open. We summarise the literature and offer our observations for the following scientists. Keywords: Polyomino, convex hull, extremal questions, plane 1Department of Applied MathematicsKatedra aplikované matematikyMatematicko-fyzikální fakultaFaculty of Mathematics and Physic