Definition of A01

Larsen's Opening, also called the Queen's Fianchetto Opening, is a chess opening starting with

1.

It is named after the Danish Grandmaster Bent Larsen. Larsen was inspired by the example of the great Latvian-Danish player and theoretician Aron Nimzowitsch (1886-1935), who often played 1.Nf3 followed by 2.b3, which is sometimes called the Nimzowitsch-Larsen Attack. It is classified under the A01 code in the Encyclopaedia of Chess Openings.