On the existence of room frames of type t u for u = 4 and 5

In this article, we describe some new constructions for Room frames and use them to show the existence of Room frames of types t 4 and t 5 . Combining the result with those of Dinitz and Stinson leads to the following: the only cases for which the existence of Room frames is undecided are those types t 4 where t = 14,22,26,34,38,46,62,74,82,86,98,122,134,146. © 1993 John Wiley & Sons, Inc.