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On Rusakov’s n -ary r s -groups

Wiesław Aleksander Dudek, Zoran Stojaković (2001)

Czechoslovak Mathematical Journal

Properties of n -ary groups connected with the affine geometry are considered. Some conditions for an n -ary r s -group to be derived from a binary group are given. Necessary and sufficient conditions for an n -ary group < θ , b > -derived from an additive group of a field to be an r s -group are obtained. The existence of non-commutative n -ary r s -groups which are not derived from any group of arity m < n for every n 3 , r > 2 is proved.

One configurational characterization of Ostrom nets

Jaromír Baštinec (1991)

Mathematica Bohemica

Bz the quadrileteral condition in a given net there is meant the following implication: If A 1 , A 2 , A 3 , A - 4 are arbitrary points, no three of them lie on the same line, with coll ( A i A j ) (collinearity) for any five from six couples { i , j } then there follows the collinearity coll ( A k A l ) for the remaining couple { k , l } . In the article there is proved the every net satisfying the preceding configuration condition is necessarity the Ostrom net (i.e., the net over a field). Conversely, every Ostrom net satisfies the above configuration...

Reflection loops of spaces with congruence and hyperbolic incidence structure

Alexander Kreuzer (2004)

Commentationes Mathematicae Universitatis Carolinae

In an absolute space ( P , 𝔏 , , α ) with congruence there are line reflections and point reflections. With the help of point reflections one can define in a natural way an addition + of points which is only associative if the product of three point reflection is a point reflection again. In general, for example for the case that ( P , 𝔏 , α ) is a linear space with hyperbolic incidence structure, the addition is not associative. ( P , + ) is a K-loop or a Bruck loop.

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