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Hetus, we have seen, are primarily divided into four classes by the Jainas viz., Aviruddha-Upalabdhi, Viruddha-Upalabdhi Aviruddha-anupalabdhi and Viruddha-anupalabdhi. Let us take these one by one.
1. The Avirudda-upalabdhi Hetu is a BidhiSadhaka one (i.c., leads to a positive conclusion) and may be of six modes. (a). The A-u-vyapya, c.g., .(Sound is subject to modification) because it is a product. (6) The A-u-karya, c.g., (There is fire in this hill grove), because smoke is seen. (c) The A-u-karana, c.g. There will be a shower of Rain) because cloud, indicative of that, is seen. (d) The A-u-purva-chara, e.g., (A Muhurta after Tishya-star will rise) because Punarvasu is seen to rise. (e) The A-u-uttarachara, c.g., (A Muhurta before Purvaphalguni-star rose) besause Uttara-phalguni is seen to rise. () The A-u-Sahachara, e.g. (There is a peculiar colour in this mango-fruit) because it has a peculiar taste. .
2. The Viruddha-upalabdhi Hetu is a NishedhaSadhaka one (i.e., leads to a negative conclusion) and may be of seven modes. (n) The V-u-Svabhava, c.g. (There cannot be only one aspect of a thing) because many aspects are seen. (6) The V-u-vyapya, c.g. (This man has not true knowledge) because he
