Architecture that suppresses the unexpected appearance of words by applying appropriate restrictions to long-term and short-term memory. The quickness of adaptation is also realized by leveraging the restriction. The architecture includes a history component for processing user input history for conversion of a phonetic string by a conversion process that output conversion results, and an adaptation component for adapting the conversion process to the user input history based on restriction(s) applied to short-term memory that impacts word appearances during the conversion process. The architecture performs probability boosting based on context-dependent probability differences (short-term memory), and dynamic linear-interpolation between long-term memory and baseline language model based on frequency of preceding context of word (long-term memory).