Discoveries (theoretical novelties) in theory of C50 Italian four knights variation of giuoco pianissimo (Italian game /giuoco piano /Italian opening), changing appraisal of its very important systems, are present in this investigation.

Summary of analysis (author's novelties are marked by symbol "AN")

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Nc3 Nf6 5.d3!

Paragraph 1: 5… h6!?

[The move 5…d6?! is bad: 6.Na4! (White stands slightly better.) …Na5 (6…Bb4 7.c3 Ba5 8.b4 White stands slightly better.) 7.Nc5 Nc4 8.dc dc 9.Qd8 Kd8 10.Ne5 Re8 11.Nf7 with a win.] 6.Be3! (White stands slightly better. It’s an author’s new appraisal.)

I

6…Be3 (6…Qe7?AN 7.a3 a6 8.b4) 7.fe Ng4! 8.Qe2 Na5!

A) 9.h3 AN Nc4! 10.dc! Nf6 11.g4 or 11.Qf2. Both black and white have weaknesses in both cases, but white stands better everywhere.

B) 9.Bb3 Nb3 10.ab d6 [10…h5 11.h3 Nh6 12.Ne5 Qh4! 13.Kd2 White stands slightly better.] 11.h3 Nf6 12.Qf2! AN or 12.g4! AN. White stands better everywhere.

II

6…Be7 AN 7.d4! (with the idea 7…Bb4?! 8.Ne5!?) …d6 (7…ed 8.Nd4 White stands slightly better.) 8.de (The another good way is 8.Bb5, that is similar to Ruy Lopez opening: C62 Old Steinitz defence. White stands slightly better.)

A) 8…Ne5 9.Ne5 de 10.Qf3 0-0 11.h3 (with the idea 12.Qg3 or 12.g4). White stands better.

B1) 8…de 9.Qd8 Bd8, and white has a well-known position of Hungarian defence C50: 1.e4 e5 2.Nf3 Nc6 3.Bc4 Be7 4.d4 d6 5.de de 6.Qd8 Bd8 7.Nc3 Nf6 8.Be3 h6.

B2) 8…de 9.Bd5 (White stands slightly better.) …Bd7! (It is a new position of Hungarian defence C50.) 10.Qe2 or 10.a3. White plans 0-0-0 and stands slightly better in both cases.

III

6…Bb6 7.Bb6! AN ab (The move 7…cb isn’t better.) 8.d4! Qe7 [8…ed 9.Nd4 (White stands slightly better.); 8…Ne4 9.Ne4 d5 10.Bb5 de 11.Ne5 (White stands better.)] 9.Ne5!

A) 9…Ne5 10.de Qb4 11.Bb3 Ne4 12.Qg4! d5 13.Qg7 Rf8 (White stands better.) 14.a3!? Qa5 15.Ba4 c6 [15…b5 16.Bb5 (16.b4!?) …c6 17.b4 Qb6 18.Ne4 (White stands better.)] 16.b4 Qa6 17.Ne4 White stands better.

B) 9…Qb4 10.Bf7 Kd8! 11.Nc6! White stands better.

IV

6…Bb4 AN 7.a3! (White stands slightly better.) 7…Bc3 (7…Ba5 8.b4!? White stands slightly better.) 8.bc White stands slightly better.

Author: Y.Bukayev