Maximal left ideals in matrix rings were studied by Stone [10]. Similar results are not necessarily valid in the general near-ring case and one of the objectives of this paper is to study these differences. Furthermore, although much is known about 2-primitivity in general matrix near-rings (Van der Walt [11]), quite the opposite is true for 0-primitivity and the other objective of this paper is to present some results on 0-primitivity in matrix near-rings in certain restricted cases.1980 Mathematics subject classification (1985 Revision): 16A76.
IntroductionMatrix near-rings were introduced in 1984 by Meldrum and Van der Walt [5]. Since then several papers ([8, 12, 11, 13, 6, 2, 3]) and theses ([7,1]) were devoted to matrix near-rings and as this field of study is still very immature, many more publications are expected to follow.The purpose of this paper is to study 0-primitivity in matrix near-rings. A good survey on 2-primitivity in matrix near-rings over any zero-symmetric near-ring has been done by Van der Walt [11]. Some results on 0-primitivity are also contained in Abbasi, Meldrum and Meyer [2], but only for a very special class of near-rings, namely the weakly distributive d.g. near-rings. Because of some complexities, we could only manage to obtain certain results in restricted cases such as finite near-rings, or near-rings having the DCCR. It seems that a considerable amount of work still needs to be done to obtain similar results in the general zero-symmetric case.The first section merely introduces some of the basic definitions, results and techniques in matrix near-rings which will be used in this paper. For more details the interested reader should consult [5], [7] and [1]. Section 2 deals with maximal left ideals in matrix near-rings and the connections they have (or do not have) with maximal left ideals in the base near-ring. A counter-example is given to show that the near-ring case does not always necessarily follow the same pattern as in the ring case.The final section is devoted, for the greater part, to finite zero-symmetric near-rings and 0-primitivity. It becomes clear from this section that in order to have a reasonable understanding of modules over matrix near-rings, it is useful if one knows whether or not such modules can be embedded into a direct sum of finitely many copies of the additive group of the base near-ring.
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