Word Discrimination Based on Bigram Co-Occurrences

Very few pairs of English words share exactly the same letter bigrams. This linguistic property can be exploited to bring lexical context into the classification stage of a word recognition system. The lexical n-gram matches between every word in a lexicon and a subset of reference words can be precomputed. If a match function can detect matching segments of at least n-gram length from the feature representation of words, then an unknown word can be recognized by determining the subset of reference words having an n-gram match at the feature level with the unknown word. We show that with a reasonable number of reference words, bigrams represent the best compromise between the recall ability of single letters and the precision of trigrams. Our simulations indicate that using a longer reference list can compensate errors in feature extraction. The algorithm is fast enough, even with a slow processor, for human-computer interaction.