These are *not* precise definitions:
an ordinary chessplayer wrote on 04/21/21 at 17:41:40:
Valvular Move - A Black (sic) move that opens one line and closes another. --Reinfeld
valve - A move that opens one line and closes another. --Wikipedia
You can also see my two objections to "valve" in the linked chesspub thread. But it turns out both of my objections were based on ignorance. (a) I failed to consider a specialist type of non-chess valve. (b) The definitions above are incomplete.
Let's consider what's not a valve.
Loschinski, Lev The Problemist (1930.Jul)
https://www.yacpdb.org/#33139 
White to move and mate in 2.
No valve in sight. yacpdb has keywords:
- Defences on same square
- Grishaw (5x)
This problem is discussed by Ramesh Abhiraman at
https://chessexpo.blogspot.com/2012/09/lev-loschinski-two-mover-black-arrival.ht... and the notes below are from him, but rearranged a little here. Note that Ahbiraman identifies two moves as "valve closing". It's curious, because I don't see why for example 1...Nfd4 is a "valve" but 1...d4 is an "interference". This was one of my objections in the linked thread above.
1.Qf2 threat 2.Qxa7#
1...Bd4 Black bishop has interfered with the fourth rank
2. Qxe2# 1... Rd4 Completing the Grimshaw
(definition: Two variations in which Bishop and Rook interfere with the other on the same square)
Black rook has vacated the h file (line-clearance) while BB's control of h6 (sic) has been interfered with, this is Grimshaw
2. Rh6# (2. Qxe2+ Rc4)
1... Nfd4 Black line-opening third rank, valve closing 4th
2. Ra3# (2. Qxe2+ Nxe2)
1... Ned4 Black line-opening third rank, valve closing 4th
2. Qa2# (2. Qe2+ Nxe2)
1... d4 Black pawn has interfered with the fourth rank
2. Bc4# (2. Qxe2+ d3)
Mistake (a) - I failed to consider a specialist type of non-chess valve. A valve as defined in chess problems is analogous to a "diverter" valve in fluid flow. In this type of valve, flow is shut off in one direction and opened in another direction.
Quote:What is a diverter valve? Diverter, selecting or directional valves are alternate names used for L-pattern flow ball valves. This is because this valve design is widely used to divert or change the flow going out through one of two different valve outlets or ports. Manual three-way L-pattern ball valves used as diverter valves are usually installed with the bottom port of the valve body as the common or flow entry port.
L-pattern flow ball valves with handles that can turn 90 degrees (a quarter turn of the handle) are also called two position valves. They can divert flow either to the left or to the right with one 90-degree turn of the handle.
https://www.industrialspec.com/about-us/blog/detail/three-way-ball-valve-t-port-... Mistake (b) - I believed the inaccurate definitions of "valve" I saw in various sources. Funk, Jacob E. The Pittsburgh Post (1923.04.01)
https://www.yacpdb.org/#8085 White to move and mate in 2.
THIS is a valve (four of them actually). yacpdb has keywords:
This problem is discussed by Brian Harley in
Mate in Two Moves: The Two Move Chess Problem Made Easy (Dover: 1970) pages 118-119 (No. 117). Originally published in 1931 by G. Bell and Sons.
1. Ng7 threat 1.Ne8#
1... Na6 2. Qxa1#
1... Nh6 2. Nxh5#
1... d6 2. Qe6#
1... d5 2. Qf1# Quote:An entertaining theme-combination is the "Valve", where Black opens and shuts, by unmasking and interference, his control lines.
In the first two variations, the Black R's are unmasked upon the threat square, while their control of their files is shut off; in the last two, the Black Q's lines are opened and closed. In the Bi-Valve Theme, much more common and easier to construct, a Black move opens up the control line of one piece, and masks the line of another, in constrast to No. 117, where the same piece is affected in both ways.
--Harley
So a "valve" is a move by black that opens one line of a black piece and closes another line of the
same black piece. And in this definition, it is exactly analogous to the turning of the handle on an L-pattern flow ball valve.
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Definition of a valve (chess problems) (Read 2173 times)
