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MatPlus.Net Forum General Name for theme of Loyd 1855 #3

### Name for theme of Loyd 1855 #3

Loyd's 1855 #3:
(= 4+6 )

with Hauptplan 1. Qh2? met by defense 1...Ra2!

The Vorplan 1. Qb8! allows 1...Ba2 preventing 2. Ne5? Be6!

But instead, after 1. Qb8 Ba2 2. Qh2! renews the Hauptplan because the Ba2 obstructs the Ra8 from its defense.

Now, this appears to be a Brunner-Dresden: "A black piece [Ra8] which parries the main plan [Qh2] is obstructed or interfered with by another black piece [Bb1], the defense of which is, however, not successful." (Encyclopedia of Chess Problems page 145).

However, in this Loyd study the same piece, the Queen, executes both the Hauptplan and the Vorplan. Also, the Hauptplan is executed without any change after the failed defense. In the other examples in the Encyclopedia of Roman and Dresden themes, different pieces are usually (always?) involved in the Hauptplan and Vorplan.

Are there other theme or theme names that describe everything the unique features that characterize this Loyd study?

Tries:
1 Qh2? Ra2!; 1 Nf7+? Kh7!
Solution:
1 Qb8 Ba2 2 Qh2 Be6 3 Kg3#; 2 ... g3 3 Kxg3#; 2 ... gxf3 3 Kg4#;
1 ... Bf5 2 Nf7+ Kh7 3 Ng5#
(and by-play)

If I understand the definitions correctly,
1 ... Ba2 2 Qh2 Be6 is, as you say, Brunner-Dresden;
the two 1 ... Ba2 2 Qh2 g~ variations are changed form Dresden (Wechselform-Dresdner).
1 ... Bf5 2 Nf7+ Kh7 is Hamburg.

Call the move that starts the Hauptplan H.

As for decoy-problems where the threat by H as try is White's move after H in the solution, how about:

Karl Fabel
Die Schwalbe, Oct 1961, no. 775
PDB P1119419
(= 3+3 )

#3

Tries:
1. Bb5? (thr 2 Bc6#) Rc8!;
1. Bc4? (thr 2 Bd5#) Rg5!
Solution: 1. Bd3! (thr 2 Be4#) Rg4 2. Bb5 Rc4 3. Bxc4 Bc5 4. Bd5#;

1. ... Re8 2. Bc4 Re5 3. Bxe5 Bh2 4. Bd5#

Both tries are thematic in that White also plays them in the solution. They and the key are all played by the same piece.

Moreover, consider Bc4. 1 Bc4? threatens Bd5#. And after 3 Bxc4, what does White play? Exactly the same move, Bd5#.

I don't know any name for this phenomenon. But it strikes me as rather boring that after White at last plays the Hauptplan's 1st move, Black can let White play its 2nd move. It's a bit like thematising unchanged mates rather than changed mates.

(3) Posted by Torsten Linß [Saturday, Jan 13, 2024 14:36]

This is not a Dresdner of any kind, because 1... Ba2 does not introduce any new defenses against the main plan.