@article{Manukian_2021, title={On Strongly Positive Multidimensional Arithmetical Sets}, volume={43}, url={http://mpcs.sci.am/index.php/mpcs/article/view/205}, abstractNote={<p>The notion of positive arithmetical formula in the signature (S,=,0), where S(x)=x+1, is defined and investigated in [1] and [2]. A multidimensional arithmetical set is said to be positive if it is determined by a positive formula. Some subclass of the class of positive sets, namely, the class of strongly positive sets, is considered. It is proved that for any n ≥ 3 there exists a 2n -dimensional strongly positive set such that its transitive closure is non-recursive. On the other side, it is noted that the transitive closure of any 2-dimensional strongly positive set is primitive recursive.</p>}, journal={Mathematical Problems of Computer Science}, author={Manukian, Seda N.}, year={2021}, month={Dec.}, pages={32–41} }