Transposition (chess)

A transposition in chess 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 opening, where a given position may be reached by different sequences of moves. Players sometimes use transpositions deliberately in order to avoid variations they dislike, lure opponents into unfamiliar or uncomfortable territory or simply to worry opponents.

In chess the verb "transpose" means shifting the game on to a different opening track from that on which it started.

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

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 Nf6
• 2. Nc3 e6
• 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

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.

See also

• Chess terminology