  Udayana claims that tarka is of five types, namely ‘self-dependence’ (ātmāśraya), ‘mutual dependence’ (anyonyāśraya), ‘circle’ (cakraka), ‘infinite regress’ (anavasthā), and ‘having an undesirable consequence’ or reductio-ad-absurdum (aniṣṭāprasaṅga). These are basically self-explanatory – the fifth, ‘prasaṅga’ is the one used to great effect by Nāgārjuna and other Mādhyamika Buddhists. Other authors give slightly different lists (see S. Bagchi 1953 for details).