Semi-Italian Opening

The Semi-Italian Opening (also known as Half Giuoco Piano, Lesser Giuoco Piano, and Paris Defence) is one of Black's responses to the Italian Game. It begins with the moves:
Black's intent is to play a Hungarian Defense with an early ...Bg4, fighting for control of the d4-square. The line was tried by Alexander Alekhine early in his career. The first recorded use in international competition was in 1846. I. A. Horowitz called the defence "solid", also writing: "It does not seem quite sufficient for equality."
The "Encyclopaedia of Chess Openings" code for the Semi-Italian is C50. 
Lines.
4.d4 Bg4.
After 4...exd4 5.Nxd4 Nf6 6.Nc3 White has the freer game according to Paul Keres, and instead of 5...Nf6, Larry Evans has suggested 5...g6 The move 4...Be7 transposes to the Hungarian Defense. 
4.h3.
White prevents Black's thematic ...Bg4. The reply 4.h3 leads to lines similar to the Hungarian Defense, for example 4... Be7 5. d4 and now:
4.Nc3.
This transposes to the game Maslov–Anatoly Lutikov, USSR 1963, which continued 4...Bg4 5.h3 Bxf3 6.Qxf3 Nf6 7.Ne2 (or 7.d3) and White stands slightly better (Keres, Miroslav Filip).
Notable games.
Rodzinski vs. Alekhine, Paris 1913:
1. e4 e5 2. Nf3 Nc6 3. Bc4 d6 4. c3 Bg4 5. Qb3 
5... Qd7 6. Ng5 
6... Nh6 7. Nxf7 Nxf7 8. Bxf7+ Qxf7 9. Qxb7 Kd7 10. Qxa8 Qc4 11. f3 (diagram) Bxf3 12. gxf3 Nd4 13. d3 
13... Qxd3 14. cxd4 Be7 15. Qxh8 Bh4# 
References.
Bibliography