Transposition (chess)

In chess, a transposition is a sequence of moves that results in a position which may also be reached by another, more common sequence of moves. Transpositions are particularly common in the opening, where a given position may be reached by different sequences of moves. Players sometimes use transpositions deliberately, to avoid variations they dislike, lure opponents into unfamiliar or uncomfortable territory or simply to worry opponents.

In chess the verb "transpose" means to shift the game onto a different opening track from which it started.

Transposition tables are an essential part of a computer chess program.

Transpositions exist in other abstract strategy games such as shogi, go, tic-tac-toe and hex.

Examples

Positions reached by different routes

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Position can arise from Queen's Gambit or English Opening.

For instance, the first position can be obtained from the Queen's Gambit:

1. d4 d5

2. c4 e6

3. Nc3 Nf6

But this position can also be reached from the English Opening:

1. c4 e6

2. Nc3 Nf6

3. d4 d5

so the English Opening has transposed into the Queen's Gambit.

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Position can arise from French Defense or Petrov Defense.

The second position shows another example. The position can arise from the French Defence:

1. e4 e6

2. d4 d5

3. exd5 exd5

4. Nf3 Nf6

The identical position can also be reached, with two extra moves played by each side, from the Petrov Defense:

1. e4 e5

2. Nf3 Nf6

3. Nxe5 d6

4. Nf3 Nxe4

5. d3 Nf6

6. d4 d5

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Position can arise from Sveshnikov Variation or Four Knights Variation in Sicilian Defence.

The third position shows another example. The position can arise from the Sveshnikov variation of the Sicilian Defence:

1. e4 c5

2. Nf3 Nc6

3. d4 cxd4

4. Nxd4 Nf6

5. Nc3 e5

6. Ndb5 d6

7. Bg5 a6

8. Na3 b5

The identical position can also be reached, with one extra move played by each side, from the Four Knights variation of the Sicilian Defence:

1. e4 c5

2. Nf3 e6

3. d4 cxd4

4. Nxd4 Nf6

5. Nc3 Nc6

6. Bf4 d6

7. Ndb5 e5

8. Bg5 a6

9. Na3 b5

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Position can arise from Sicilian Defence or King's Indian Defence.

The position on the right, featuring a Maróczy Bind, can be reached from the Sicilian Defence:

1. e4 c5

2. Nf3 d6

3. d4 cxd4

4. Nxd4 g6

5. c4 Bg7

6. Nc3 Nf6

7. f3 Nc6

8. Be3 0-0

The identical position can also be reached from the King's Indian Defence:

1. d4 Nf6

2. c4 g6

3. Nc3 Bg7

4. e4 0-0

5. f3 d6

6. Be3 c5

7. Nge2 cxd4

8. Nxd4 Nc6

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Position can arise from Sicilian Defence or Pirc Defence.

The position on the right can be reached from the Sicilian Defence:

1. e4 c5

2. Nf3 d6

3. d4 cxd4

4. Nxd4 Nf6

5. Nc3 g6

6. Be3 Bg7

7. Be2 Nc6

8. 0-0 0-0

The identical position can also be reached from the Pirc Defence:

1. e4 d6

2. d4 Nf6

3. Nc3 g6

4. Nf3 Bg7

5. Be2 0-0

6. 0-0 c5

7. Be3 cxd4

8. Nxd4 Nc6

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Isolani position which can arise from the Queen's Gambit, Nimzo-Indian and Caro–Kann among other openings.

The position on the right, featuring an isolani can be reached by many different openings and move orders. For example, there's the Nimzo-Indian Defence:

1. d4 Nf6

2. c4 e6

3. Nc3 Bb4

4. e3 0-0

5. Bd3 c5

6. Nf3 cxd4

7. exd4 d5

8. 0-0 dxc4

9. Bxc4 Nc6

10. a3 Be7

Caro–Kann Defence:

1. e4 c6

2. d4 d5

3. exd5 cxd5

4. c4 Nf6

5. Nc3 e6

6. Nf3 Bb4

7. Bd3 dxc4

8. Bxc4 0-0

9. 0-0 Nc6

10. a3 Be7

Transposition possibilities of some openings

Some openings are noted for their wide range of possible transpositions, for example the Catalan Opening and Sicilian Defence.

For a simple example, the opening moves 1.d4 e6 can transpose very quickly into a wide range of openings, including:

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Queen's Gambit Declined, after 2.c4 d5. The QGD itself offers a wide range of transpositional possibilities.

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

After 2.c4 Nf6. This could develop in many ways, including: Queen's Gambit Declined, Nimzo-Indian Defense, Queen's Indian Defense or Modern Benoni Defense.

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Dutch Defense, after 2.c4 f5

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

English Defense, after 2.c4 b6

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

French Defence, after 2.e4 d5

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Franco-Benoni, after 2.e4 c5. This can transpose into various types of Benoni Defense after 3.d5, into the Alapin Variation of the Sicilian Defense after 3.c3, or into main lines of the Sicilian Defense after 3.Nf3 cxd4 4.Nxd4.