Pizza by the slice is coming to five 7-Eleven convenience stores in Los Angeles in November as part of a test by owner Southland Corp. The nation's largest convenience store operator said it will test the idea in Los Angeles and Detroit . . . Tylan Corp., a semiconductor equipment manufacturer, announced a 25% staff reduction, involving 59 indirect and administrative employees, at the company's headquarters and principal manufacturing facility in Carson . . . Alaska Air Group and Jet America Airlines said their boards of directors have approved a previously announced agreement for the purchase of Jet America by Alaska Air Group at $3.25 per share . . . Standard & Poor's said it upgraded Allied Stores' senior debt to A+ from A and subordinated debt to A from A-, reflecting "a steady trend of improving credit-quality measurements."