Semi-Open Deep Lines
The deep-line archive of Volume B: named sub-variations of the Sicilian, Caro-Kann, Pirc, Modern, Alekhine and Scandinavian — the lines that decide real games once both players know the first ten moves.
If you want an opening that fights from the very first moves, Semi-Open Deep Lines is a superb candidate — principled, sharp and endlessly instructive.
After 4.Nxd4 the position resolves into a fluid centre — one side has staked a central pawn the other must decide how to challenge, so the structure is still being negotiated, with the d-file half-open for White and the c-file half-open for Black.
The moves
After 4. Nxd4 — Semi-Open Deep Lines main line
Position breakdown
A factual read of the position after the main line — the files, the centre, the pawn structure and king safety that decide how the middlegame is played. These are computed from the actual board, not generic advice.
Files
Centre control
Fluid centre
The d4/d5/e4/e5 squares — who occupies the centre decides how open the game becomes.
Pawn skeleton
Pawns only — the structure that explains every open file and majority at a glance.
Material level
Queenside pawns 3–2
Kingside pawns 3–3
Development
Knight active
No minor pieces developed yet
King safety
White king e1
Uncastled — take care
Black king e8
Uncastled — take care
Computed from the final position of the main line above — 7 plies, black to move.
Strategic ideas
Ideas for White
Master the move-order subtleties: most of these lines transpose or diverge by a single tempo, and knowing which is which is preparation itself.
Ideas for Black
Pick one line per main system and drill it deep — Semi-Open games reward specialists over generalists.
Main variations (72)
Najdorf, 6.Be3 Ng4 Setup
B90The Ng4 strike: hitting e3hitting the bishop pair immediately.
Najdorf, 7.Qd3 Setup7.Qe2 Setup
B94The Qe2 setup: avoiding the O-O-O commitments in the 6.Bg5 complex.
Najdorf, Hungarian Attack
B90The h3/h5 mirror: both sides grab kingside space in the Adams complex.
Najdorf, Perenyi Attack
B97The Rb1 refinement of the Poisoned Pawn — the sharpest practical try.
Yugoslav, 9.O-O-O Main
B76The O-O-O tabiya before the mutual storms commit.
Dragon, Classical with Be3
B73The Qd2 classical setup: patient build-up with f4 or h4 to follow.
Dragon, 6.f3 Yugoslav Direct
B70The early f3: committing to the Yugoslav at maximum speed.
Classical, 6.Bc4 Sozin
B56The Sozin's direct approach: the bishop hits f7 from move six.
Classical, Boleslavsky 7.O-O
B58The castling-first Boleslavsky: solid, flexible, strategic.
Rauzer, 7...a6 9.f4
B69The Bxf6 structure decision: wrecked pawns versus the b-file.
Sveshnikov, 8.Na3 b5 9.Nd5
B33The classical Sveshnikov tabiya: knights and bishops in eternal tension.
Sveshnikov, 9.c49.Bxf6 Structure
B33The structural trade: gxf6 ruins the kingside but fills the d5 hole.
Sveshnikov, 9.c4 Setup9.cxb5? skip
B33The Nd5 outpost: the knight parks on d5 and White grinds the dark squares.
Scheveningen, 7.Qd2 Setup
B80The Qd2 setup: castling long is coming — the race begins immediately.
Taimanov, 6.Qd26.Be3 b5? use 6...a6 7.Qf3 Setup
B48The ...Ne5 counter against the Qf3 setup — tactics on the light squares.
Kan, 6.Bc4 Setup
B43The Bb3 retreat: keeping the a2-g8keeping the f7 pressure while dodging tempo hits.
Kan, 6.a4 Setup
B43The a4 clamp: slowing ...b5 to a crawl in the Kan structures.
Four Knights, 6.Ndb5 Main
B45The Bf4 pinthe Bf4 development hitting c7pressuring d6 with tempo.
Alapin, 2...Nf6 3.e5 Nd5 4.d4 Main
B22The main Alapin tabiya: the big centre versus the ...d6/...Nc6 counterstrikes.
Alapin, 2...Qa5?!2...d5 4.Bd3? skip — 2...Nc6 Setup
B22The early queen sortie: ...Qxd5 hits c4hits the d4 pawn with tempo.
Smith-Morra, 4.Qxd4 Setup
B21The queen-recapture line: faster development, faster attacks.
Closed Sicilian, 6.f4 Setup
B23The f4 wedge: space first, attacks later in the Closed complex.
Closed Sicilian, ...e6 Setup
B23The ...e6/...d5 strike: central counterplay against the Closed setup.
Rossolimo, 5.d3 Main
B31The pure development setup: no pawn grabs, just the slow squeeze.
Rossolimo, 4.O-O Nf6
B30The patient setup: keeping the bishop's options open for another move.
Moscow, 4.Bxd7+ Qxd7 5.c3
B52The c3/Nd2the c3 build-up supporting a future d4 at full safety.
Caro-Kann, Advance Short Setup
B12The Short setup: flexible knight development before committing d4before committing the centre.
Caro-Kann, Advance c3 Setup
B12The c3 support: solidifying the wedge before Black's counterplay forms.
Caro-Kann, Panov Main
B14The ...Bg4 pin: the classical Panov middlegame tension.
Caro-Kann, Two Knights 4.h3
B11The h3 probe: asking the bishop to decide immediately.
Caro-Kann, Classical 5.Bd35.Ng3 h6 Setup
B18The h4/h5 storm: the classical attacking plan against the g6-bishop.
Pirc, Austrian 6.e56.Bc4 Setup
B09The Bc4 development: eyeing f7eyeing the kingside diagonals.
Pirc, Austrian 7.e5 Strike
B09The e5 wedge: space now, weaknesses later — sharp Austrian play.
Modern, 150 Attack Main
B06The full 150 Attack fortress: f3/Be3/Qd2 and the queenside castle storm.
Modern, 3...c5 Strike
B06The early ...c5 strike: Benoni-style counterplay at once.
Alekhine, Chase 5.f4
B02The f4 support: solidifying e5 while the knight sits on d5.
Alekhine, Modern Bb3 Setup
B04The Bb3 retreat: keeping the f7keeping the diagonal pressure.
Alekhine, 4.exd6 Setup
B03The early trade: solid structure versus the open c-fileversus quick development.
Scandinavian, 3...Qa5 5.Bf44.d4 Nf6 5.Bd2 Setup
B01The Bf5 setup: solid development with the active bishop.
Scandinavian, Icelandic Main
B01The bishop recapture: keeping the light squares in the Icelandic gambit.
Scandinavian, Qd6 Main
B01The ...a6 prophylaxis: stopping Bb5 pins in the Qd6 system.
Scandinavian, 3...Qd8 Setup
B01The knight-recapture setup: clean development before the queen returns.
Modern, Robatsch ...c6 Setup
B06The ...c6 support: solid, solid, solid — and ready for ...b5 expansion.
Pirc, Czech ...c6 Setup
B07The Czech Qa5 setup: pressure on a5-d2on the a5-e1 diagonal.
Nimzowitsch, 2...d5 Setup
B00The e5 wedge: space against the knight-hop provocation.
St. George Main Setup
B00The queenside expansion setup — the St. George's flag planted.
Owen, ...Bb7 Main
B00The solid Owen setup: ...e6 support before the ...Bb7 pressure bites.
Borg, 2.d4 Bg7 Setup
B00The Borg fianchetto: absurd, aggressive, and occasionally brilliant.
Caro-Kann, Gurgenidze ...b53.Nc3 g6 Setup
B10The g6 setup: the fianchetto defence inside the Caro-Kann.
Caro-Kann, Advance 5.f4 Setup
B12The f4 support: solidifying the wedge in the Advance structure.
Caro-Kann, Panov Classical
B14The classical Panov development: solid, theory-rich, strategic.
Pirc, Classical 7.c3 Setup
B08The c3 support: solidifying d4 against the Bg4 pin pressure.
Modern, Two Knights ...d5 Strike
B06The immediate ...d5 strike: central counterplay before White settles.
Dragon, 9.Bc4 Yugoslav Main
B77The classical Yugoslav castling: the h-pawn avalanche ready.
Dragon, 10.h4 Yugoslav Storm
B79The h4 storm: the deepest Yugoslav battlegrounds.
Najdorf, English Attack 11.g4
B90The g4! launch: the main line's kingside avalanche begins.
Sveshnikov, 9.Bxf6 gxf6 10.Nd5
B33The Nd5 parking manoeuvre: the knight anchors and the dark-square grind begins.
Sicilian, Kan 6.Be2 Setup
B43The Be2 setup: solid development in the Kan structures.
Sicilian, Taimanov 5.Nb5 Setup
B44The Nb5 probe: hitting d6 and c7 early.
Sicilian, Najdorf 6.a4 Setup
B90The a4 clamp: stopping ...b5 at the source.
Sicilian, Dragon Levenfish Main
B71The ...Qa5+ check: the Levenfish's sharp counter.
Caro-Kann, Fantasy 4.exd5
B12The pawn-recapture line: the Fantasy's main structure.
Caro-Kann, Classical 7.Nf3 Main
B18The Nf3 development: the classical main tabiya.
Caro-Kann, Panov 7.Bd3
B14The Bd3 setup: the Panov's standard development.
Pirc, Austrian 5.Nf3 Setup
B09The Nf3 development: the Austrian's main setup.
Modern, Standard Setup
B06The Nf3 development: the Modern's standard setup.
Alekhine, Four Pawns 5.f4 Setup
B03The f4 wedge: the Four Pawns' space race.
Alekhine, Chase 4.c5 Setup
B02The c5 wedge: the Chase's signature structure.
Scandinavian, Qd6 Setup
B01The Qd6 retreat: the modern Scandinavian's main setup.
Scandinavian, Qa5 Setup
B01The Qa5 setup: the classical Scandinavian structure.
Nimzowitsch, 2.Nf3 Setup
B00The Nf3 development: the safe answer to the knight hop.
Owen, 2.d4 e6 Setup
B00The ...e6 setup: solid support for the Owen fianchetto.
Plans & pawn structures
- 1White plays down the d-file — with no White pawn there, a rook lift and pawn lever turn this file into direct pressure on d7.
- 2Black's counterplay runs down the c-file: it is half-open for Black, so the rooks swing there to hit c2 while White is busy elsewhere.
- 3The centre is still fluid: decide early whether to lock it with a pawn advance or dissolve it with an exchange, because that choice picks the whole middlegame plan for you.
Typical middlegame structures
The main line leads to a fluid centre — one side has staked a central pawn the other must decide how to challenge, so the structure is still being negotiated. It leaves the d-file half-open for White, the c-file half-open for Black — that is where the rooks belong and where the middlegame is decided. On the pawns, Black holds a kingside pawn majority — the long-term trump to nurse into the endgame.
Traps & tactical motifs
Every sharp opening has its traps — study the forcing lines around the centre and the f7/f2 squares before playing this in rated games.
Watch the typical motifs: pins against the pinned piece, knight forks after the natural captures, and queen sorties to a2/g2-style squares.
How to Play Against the Semi-Open Deep Lines
- Neutralise the c-file before Black owns it: challenge with your own rook, or close the file with a pawn so the opponent's main artery of play dries up.
- As White, strike at the fluid centre immediately with your own central pawn or piece pressure, before the opponent locks it into a shape that favours them.
Study plan & who it's for
Expect to invest a weekend or two into the main lines. In return you get a fighting system that scales all the way to master level for Black players.
Play through the main line above until the piece setup feels natural.
Learn the two or three critical pawn breaks for both sides.
Drill one variation at a time — always connecting moves to plans.