A wordlist is useful for solving word puzzles, such as the one in . Our program iterates through every word and, for each one, checks whether it meets the conditions. It is easy to check obligatory letter and length constraints (and we'll only look for words with six or more letters here). It is trickier to check that candidate solutions only use combinations of the supplied letters, especially since some of the supplied letters appear twice (here, the letter v ). The FreqDist comparison method permits us to check that the frequency of each letter in the candidate word is less than or equal to the frequency of the corresponding letter in the puzzle.
One factor of obvious relevance is motivation, and studies have been conducted regarding motivation to learning second language,      and the relationship of fossilization to the learner's communicative needs.    Arguments have emerged regarding adult learners' general lack of empathy with target language native speakers and culture. According to Guiora et al.,  adults do not have the motivation to change their accent and to acquire native-like pronunciation. Unlike children, who are generally more open to target language culture, adults have more rigid language ego boundaries. Thus, adults may be inclined to establishing their pre-existing cultural and ethnic identity, and this they do by maintaining their stereotypical accent.  Notwithstanding this, there is a lack of needed research, particularly regarding achievement motivation, especially considering that fossilization can be considered the most distinctive characteristic of adult SLA.