Since no one cares to correct me, let me do it
myself. Vadim indignantly replies to Oks (Osip Lvovich Oksman, who said
that he met Vadim's father twice: in the days of the First Duma,
1905-6, and in 1917, after the February Revolution) that his father died
six months before he was born (LATH, Part II, ch. 4). Vadim's birthday must
be the same as that of VN: April 23, 1899.
I'm not sure anymore that Vadim's family name is
Blagidze. After all, he does refer once to lieutenant Starov, his first wife's
murderer, who blew his brains out, as "Blagidze:" "The hole in
Blagidze's mind had caused a complete set of recent memories to
escape..." (I, 13). I have another idea about Vadim's surname, but it has
yet to be tested.
Happy New Year!
Alexey