The Ragozin Defence is characterized by the moves
1.d4 Nf6 2.c4 e6 3.Nf3 d5 4.Nc3 Bb4
The QGD Ragozin Defence offering Black active play from the start, has enjoyed a resurgence in recent times. It is at the forefront of chess theory. With the surge of 3.Nf3 as an answer to Nimzo-Indian set-ups and with the difficulties that the black players have suffered with the Queen’s Indian, it was natural to turn to the Ragozin as a solid and reliable way to counter white’s set-ups. The Ragozin is being played by every top grandmaster in the world.
Viacheslav Vasilyevich Ragozin (8 October 1908 – 11 March 1962) was a Soviet chess Grandmaster, an International Arbiter of chess, and a World Correspondence Chess Champion. He was also a chess writer and editor. His contributions to opening theory mainly concerned the development of systems by which Black could achieve equality in the Queen's Gambit and Nimzo-Indian complexes.
Queens Gambit Declined: Ragozin Variation
Queens Gambit Declined: Ragozin, Vienna Variation