I have been trying to see if I am missing any important data on the dates of Vidyānandin and Vācaspatimiśra. M. A. Dhaky noted (in Nirgrantha vol. 2) that Vidyānandin appears to refer to, and quote, Vācaspati. Vidyānandin is put at 900–950 by Dhaky (the "later date" as summarized in Himal Trikha's Perspektivismus und Kritik). Vācaspati himself is usually dated by reference to the date 898 found in the Nyāyasūcīnibandhana (hence either 976 or 841) but Muroya ("Apropos the Nyāyasūcīnibandhana") doubts the ascription to Vācaspati. The other termini ad quem mentioned in Acharya's Tattvasamīkṣā edition are Śrīdhara (991) and Durvēkamiśra (975–1025). Acharya favors 950–1000 for Vācaspati's floruit, but this seems incompatible with his being cited by Vidyānandin, if indeed Vidyānandin lived before 950 (I would say before 959, since Sōmēśvara seems to use him as a source in the Yaśastilakacampū). Similarly incompatible with this datum (it seems to me) is Muroya's argument (in "Bhāsarvajña's interpretation of bhāva eva nāśaḥ") that Vācaspati was a contemporary of Jñānaśrīmitra (975–1025).

I would appreciate it if anyone has any further references that might help in resolving this puzzle, or any opinions about the balābala of these arguments.

Andrew