EUDML

Currently displaying 1 – 8 of 8

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On The Essential Flats Of Geometric Lattices

Dragan M. Acketa — 1979

Publications de l'Institut Mathématique

On minimal area augmentation of digital convex $n$ -gons

Snežana Matić-Kekić; Dragan M. Acketa — 1998

Mathematica Slovaca

A family of 4-designs on 26 points

Dragan M. Acketa; Vojislav Mudrinski — 1996

Commentationes Mathematicae Universitatis Carolinae

Using the Kramer-Mesner method, $4$ - $(26, 6, λ)$ designs with $P S L (2, 25)$ as a group of automorphisms and with $λ$ in the set ${30, 51, 60, 81, 90, 111}$ are constructed. The search uses specific partitioning of columns of the orbit incidence matrix, related to so-called “quasi-designs”. Actions of groups $P S L (2, 25)$ , $P G L (2, 25)$ and twisted $P G L (2, 25)$ are being compared. It is shown that there exist $4$ - $(26, 6, λ)$ designs with $P G L (2, 25)$ , respectively twisted $P G L (2, 25)$ as a group of automorphisms and with $λ$ in the set ${51, 60, 81, 90, 111}$ . With $λ$ in the set ${60, 81}$ , there exist designs which possess all three considered groups...