Institution: | a Lamar University, Department of Mathematics, Beaumont, TX 77710, USA b Opole University, Institute of Mathematics and Informatics, ul. Oleska 48, 45-052 Opole, Poland c Texas A&M University, Department of Mathematics, College Station, TX 77843, USA d Nipissing University, Faculty of Arts and Sciences, North Bay, Ontario P1B 8L7, Canada e University of Saskatchewan, Department of Mathematics, Saskatoon, Saskatchewan S7N 0W0, Canada |