Tirukkannapuram Vijayaraghavan

Thirukannapuram Vijayaraghavan
Born	30 November 1902
Died	April 20, 1955(1955-04-20) (aged 52)
Occupation	mathematician

Tirukkannapuram Vijayaraghavan (Tamil: திருக்கண்ணபுரம் விஜயராகவன்; 30 November 1902 – 20 April 1955) was an Indian mathematician from the Madras region. He worked with G. H. Hardy when he went to Oxford in mid-1920s on Pisot–Vijayaraghavan numbers. He was a fellow of Indian Academy of Sciences elected in the year 1934.

Vijayaraghavan was well versed in Sanskrit and Tamil. He was a close friend of André Weil. He served with him in Aligarh Muslim University. He later moved to the University of Dhaka in protest at Weil's firing from AMU.

Vijayaraghavan proved a special case of Herschfeld's theorem on nested radicals: For ${\displaystyle a_{n}>0}$

converges if and only if

where ${\displaystyle {\overline {\lim }}}$ denotes the limit superior.

...
Wikipedia