In order to develop desirable software, defining problems is the most important among all software development activities. In this paper, we propose a model, namely Butterfly model, which defines various kinds of problems by means of contradiction relationships. Our Butterfly model is based on TRIZ and is useful for creative problem solving. By using the proposed model, we review 4 problems and then, solve the problems by eliminating the contradictory relationships. All the problems in this paper have the same features in some aspects. All can be defined as a problem having a trade-off between ‘volume’ and ‘efficiency’. In other words, we can find some problem frames. Finally, we apply the dimension change principle and the use of intermediary principle of TRIZ to solve the problems.