Tributes poured in on Monday for the visionary co-founder of the Russian search engine Yandex, Ilya Segalovich, who died over the weekend of cancer aged 48. Along with his former classmate Arkady Volozh, Segalovich turned Yandex into Russia’s most popular search engine and a company valued at $10 billion on the New York stock exchange. “I do not know how his encyclopaedic knowledge of technologies and his pure vision for the product can be replaced,” said Volozh as he confirmed his co-founder’s death.