The single-finger keyboard layout problem

The problem of designing new keyboards layouts able to improve the typ-ing speed of an average message has been widely considered in the literature ofthe Ergonomics domain. Empirical tests with users and simple optimizationcriteria have been used to propose new solutions. On the contrary, very fewpapers in Operations Research have addressed this optimization problem. Inthis paper we firstly resume the most relevant problems in keyboard design,enlightening the related Ergonomics aspects. Then we concentrate on key-boards that must be used with a single finger or stylus, like that of PortableData Assistant, Smartphones and other small devices. We show that the un-derlying optimization problem is a generalization of the well known QuadraticAssignment Problem (QAP). We recall some of the most effective metaheuris-tic algorithms for QAP and we propose some non trivial extensions to thekeyboard design problem. We compare the new algorithms through compu-tational experiments with instances obtained from word lists of the English,French, Italian and Spanish languages. We provide on the web benchmarkinstances for each language and the best solutions we obtained.