SpellCheF : Spelling Checker and SpellCheF : Spelling Checker and SpellCheF : Spelling Checker and SpellCheF : Spelling Checker and SpellCheF : Spelling Checker and Corrector for Filipino Corrector for Filipino Corrector for Filipino Corrector for Filipino Corrector for Filipino Cheng, Charibeth, Alberto, Cedric Paul, Chan, Ian Anthony and Querol, Vazir Joshua Cheng, Charibeth, Alberto, Cedric Paul, Chan, Ian Anthony and Querol, Vazir Joshua Cheng, Charibeth, Alberto, Cedric Paul, Chan, Ian Anthony and Querol, Vazir Joshua Cheng, Charibeth, Alberto, Cedric Paul, Chan, Ian Anthony and Querol, Vazir Joshua Cheng, Charibeth, Alberto, Cedric Paul, Chan, Ian Anthony and Querol, Vazir Joshua College of Computer Studies De La Salle University - Manila SpellCheF is a spell checker for Filipino that uses a hybrid approach in detecting and correcting misspelled words in a document. Its approach is composed of dictionary-lookup, n-gram analysis, Soundex and character distance measurements. It is a plug-in to OpenOffice Writer. Two spelling rules and guidelines, namely, the Komisyon sa Wikang Filipino 2001 Revision of the Alphabet and Guidelines in Spelling the Filipino Language (or KWF), and the Gabay sa Editing sa Wikang Filipino (or GABAY) rulebooks, were incorporated into the system. SpellCheF is composed of three modules, namely the lexicon builder, the detector and the corrector. These three modules used both manual-formulated and learned rules to carry out their tasks. Test results showed that the lexicon builder was able to correctly categorize words based on the spelling rules used. It also generated three databases, namely, (1) the KWF-compliant words database, (2) the Gabay-compliant words database, and (3) the database of words common to both KWF and GABAY. The detector module had an overall error rate of 7% in identifying misspellings. Furthermore, it was observed that n-gram analysis performed better than the simple dictionary look-up. The corrector module had a 94% accuracy rate in generating word suggestions. Results also showed that using the soundex code, more suggestions were generated compared to the use of n-gram analysis. However, the first character of the soundex-based suggestions was always the same are the first character of the misspelled word. Keywords: Filipino language, spelling checker, spelling corrector JOURNAL OF RESEARCH IN SCIENCE, COMPUTING, AND ENGINEERING Vol. 4 No. 3 December 2007 De La Salle University–Manila INTRODUCTION A spell checker is a feature found in most document-related applications. It is used to ensure that words in a given document are correctly spelled. Simple spell checkers use a large lexicon containing correctly spelled words. Each word in the document is checked against this lexicon. If a word is not found in the lexicon, it is considered misspelled. A spelling corrector may be included in spell checker, to generate suggestions that may replce the misspelled word. (Gratilla, 2006) implemented a tri-gram-based Tagalog spell-checker. It eliminated the use of a lexicon to perform spell checking. It learns the acceptable tri-grams in Tagalog given several Tagalog texts. Instead of checking the spelling of word itself, it determines if the tri-grams contained in a word are acceptable. Filipino is the term used in 1973 and 1987 Philippine Constitutions to designate as the national language. It is sometimes referred to as Tagalog. But the two languages are different. Orthographically, Tagalog has 20 letters while