Infohunter: <myschkin: PS: question to the composers ... what is a <Bristol> and how did this <thematic idea> (?) got its name? thx in advance>I am no composer but, as my user name indicates, I do have a bit of information at my disposal.
According to my source, which is Hooper and Whyld's _Oxford Companion to Chess_, 1987 edition, a Bristol Clearance Theme, or simply Bristol Theme, runs as follows: "Piece A is moved along a line; another line-piece, B, is moved to this line and then along it towards piece A, to or beyond the square occupied by that piece initially."
To be sure, this abstract definition sounds rather like something you might hear from some college math professor. Not to worry: The editors supply us with some concrete information:
White to play and mate in three. (Frank Healey, 1861) [bad FEN: 8/1n3Np1/1N4Q1/1bkP4/p1p2p2/P1P2R2/3P2PK/B3R4]
(Note: For some reason I cannot get the FEN to produce a diagram for this post, but you get the idea.)
We are informed that this is one of a set that won first prize at the Bristol Tourney for composers in 1861, hence the name.
The solution, incidentally, is 1.Rh1 Be8 2.Qb1 Bb5 3.Qg1.
I hope this answers your questions satisfactorily, <myschkin>. Pity it took so long.