Djoko Suprijanto

On the strong non-rigidity of certain tight Euclidean designs

We study the non-rigidity of Euclidean t-designs, namely we study when Euclidean designs (in particular certain tight Euclidean designs) can be deformed keeping the property of being Euclidean t-designs. We show that certain tight Euclidean t-designs are non-rigid, and in fact satisfy a stronger form of non-rigidity which we call strong non-rigidity. This shows that there are plenty of non-isomorphic tight Euclidean t-designs for certain parameters, which seems to have been unnoticed before. We also include the complete classification of tight Euclidean 2-designs.

On Ramsey (3K2, K3) – minimal graphs

The Ramsey graph theory has many interesting applications, such as in the fields of communications, information retrieval, and decision making. One of growing topics in Ramsey theory is Ramsey minimal graph. For any given graphs G and H, find graphs F such that any red-blue coloring of all edges of F contains either a red copy of G or a blue copy of H. If this condition is not satisfied by the graph F − e, then we call the graph F as a Ramsey (G, H) – minimal. In this paper, we derive the properties of (3K2, K3) – minimal graphs. We, then, characterize all Ramsey (3K2, K3) – minimal graphs.

The complete list of Ramsey

Let

(2K_2,K_4)

F, G,

-minimal graphs

and

On Unicyclic Ramsey (mK2, P3)−Minimal Graphs☆

H

A characterization of the corona product of a cycle with some graphs based on its f-chromatic index

be non-empty graphs. The notation

On Ramsey \((mK_2,H)\)-Minimal Graphs

F \rightarrow (G,H)

Codes over infinite family of rings : Equivalence and invariant ring

means that if all edges of

ΘS-cyclic codes over Ak

F