On Real Time One-Way Cellular Array

Abstract We present a condition on the languages to be recognizable in real time on a one-way cellular array. As an application we show that the language L = L 1. L 1 with L 1 = { w : w = 1 u 0 u or w = 1 u 0 y 10 u with y ϵ {0, 1} ∗ and u > 0} , is not a real time OCA language although L 1 is a real time OCA one and a context free one. The consequence is that the class of real time OCA language is not closed under concatenation and does not contain all context free languages.