The compact presentation for the alternating central extension of the q-Onsager algebra

The q-Onsager algebra Oq is defined by two generators and relations, called the q-Dolan/Grady relations. We investigate alternating central extension of Oq. was introduced Baseilhac Koizumi, who it current Recently Shigechi gave a presentation attractive, but multitude relations makes unwieldy. In this paper we obtain that involves subset original set very manageable call compact This resembles for positive part Uq(slˆ2).