let $alpha$ be an endomorphism and $delta$ an $alpha$-derivationof a ring $r$.  in this paper we  study the relationship between an$r$-module $m_r$ and the  general polynomial module  $m[x]$ over theskew polynomial ring $r[x;alpha,delta]$. we introduce the notionsof skew-armendariz modules and skew quasi-armendariz modules whichare generalizations of $alpha$-armendariz modules and extend thecla...

In PG(2, q), q a prime power, we study the set T of Baer subplanes that contain a fixed triangle PQR. To construct a linear rank 2–geometry over T , we determine the dihedral groups, their orders and possible extensions that are generated by the involutions of two Baer subplanes of T . If q+1 is an odd prime, the (q+1)2 Baer subplanes through the triangle PQR are the points of an affine plane A...

We study quasi-Hopf algebras and their subobjects over certain commutative rings from the point of view of Frobenius algebras. We introduce a type of Radford formula involving an anti-automorphism and the Nakayama automorphism of a Frobenius algebra, then view several results in quantum algebras from this vantage-point. In addition, separability and strong separability of quasi-Hopf algebras ar...

It was pointed out in my last paper that there are rings whose real closure ∗ are not unique. In [4] we also discussed some example of rings by which there is a unique real closure ∗ (mainly the real closed rings). Now we want to determine more classes of rings by which real closure ∗ is unique. The main results involve characterisations of domains and Baer regular rings having unique real clos...

Quasi-elastic responses in nuclear matter and in 12C and 40Ca nuclei are calculated in ring approximation to investigate the finite size effects on the electromagnetic quasi-elastic responses. A method to simulate these effects in infinite systems calculations is proposed. The sensitivity of the results to the various terms of the residual interaction is studied. The results of nuclear matter R...