Text Entry in PDAs with WtX

Massimo Ancona*, Gianluca Quercini*
Università di Genova, Department of Computer Science (DISI), Via Dodecaneso 35, 16146 Genova, Italy.

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Ancona et al.; Licensee Bentham Open

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Università di Genova, Department of Computer Science (DISI), Via Dodecaneso 35, 16146 Genova, Italy; Tel: +39 010 353 6605; Fax: +39 010 353 6699; E-mail:, E-mail:


Size is a mixed blessing for portable devices. While they feature a wide range of applications and services that can be used anywhere and anytime, their user interface is poor, hampered by the screen size. Furthermore, portable devices are meant to be used everywhere, even in uncomfortable situations (while standing up or walking for instance). Consequently, some tasks get hard to be accomplished. One of them is text entry, which is still far from being as comfortable as on desktop PCs. Different solutions have been envisaged, including small hardware keyboards, software (also called virtual) keyboards, predictive input techniques and handwriting recognition systems. In this paper we give a thorough overview of our text entry tool Word Tree version X (WtX), especially focusing on recent improvements. The new version of WtX features a handwriting recognition system and a mechanism (which we called First-Third-Last rule or simply FTL rule) forcing users to insert the characters of a word so as to improve text prediction.

Keywords: Text entry for PDAs, Text prediction, Abbreviation systems, Virtual Keyboards, Handwriting recognition systems, Comfortable Text Entry.