Upper bounds for permanents of $\left( {0,\,1} \right)$-matrices

This invention relates to a printing device of the type having a carriage which supports a printing roll. In order to perform the printing operation, the carriage is pivotally and slidably mounted on a slide rod. An arm of the carriage is mounted in a housing and is provided with a guide roller that is located in the same vertical plane as the printing roll. The guide roller cooperates with a guide means that extends parallel to the slide rod to keep the printing roll in engagement with a printing anvil and to enable the printing roll to swing upwardly into a raised position when arriving at one of the ends of the slide rod.