[fromageGB]

I am surprised that I have not come across this concept. For the first discard to indicate a suit preference for one of the other suits, Lavinthal(McKenney) is the most popular round here. This suffers from the fact that to signal for the highest ranking suit, a high card must be thrown, and this is not usually a good idea. The improvement on this that some people play is revolving discards, because then there is always the option of throwing a low card in a low ranking suit. However, sometimes you cannot spare a card in that suit, perhaps because you are keeping length with dummy to avoid giving a free trick there.

Another common problem with high or low signalling is misinterpretation. It can be difficult to find a low card when the 8 is your lowest. Even without that, a card that is high or low in the context of your hand may seem the opposite to partner, perhaps because declarer has all the low cards concealed.

Why don't people play parity suit preference? Remembering the expressions "even-up" and "odD Down", you can play parity revolving, where an odd card means "go down" cyclically, while an even card means "go up". Playing parity lavinthal, an even card means the higher ranking of the other two suits, while an odd card means the lower ranking. (There is now no advantage in playing one or the other, both are equally as effective.)

One advantage is that you can always signal with low cards, not needing to waste a high one. Even more important, there is no ambiguity : a 6 is always even, whether partner may think it high or low.

If you wanted to, or course, you can add modifications such as a 2,3 or 4 are neutral cards, implying no signal, or a low card followed by a higher on the second discard cancels the initial unintentional signal, but whatever, it seems superior to play parity rather than magnitude as the signal.

Why is this not done? Why have I not come across it?

(You may prefer to play Italian odd/even or Dodds, or something similar, but that is a different question.)

[ahydra]

Some people at uni used to play "mod-3 discards", where 2, 5 or 8 asks for the suit below, 3, 6 or 9 for the suit discarded, and 4, 7 or 10 for the suit above.

With any discard system you will always find yourself short of the card you need at some point. For example, with "parity McKenney" if you're discarding on diamonds and want a spade, but hold only odd hearts and even clubs, you're stuck. Personally I've found reverse attitude by far the most reliable (since it's safe most of the time to throw a high card in a suit you don't want, e.g. 9xx).

ahydra

[helene_t]

fromageGB, on 2013-November-01, 08:14, said:

a 6 is always even, whether partner may think it high or low.

Say you have 853 and you want to show an even card but you can't afford the 8. If that makes you chose 5 or 3 at random then you are even worse off than those who wanted to show a "high" card, since at least 5 is higher than 3.

So you should agree that the order is 24689753, i.e. 5 is more even than 3. Basically, you play the highest card when you have only the wrong parity and the lowest when you have only the right parity. Now you have the same level of accuracy as someone who plays standard SP.

But parity is slightly more economical than high/low. Say you have 9832. You can now give a clear and economic signal by playing either the 2 or the 3. Those who want to show a high card are forced to chose between an unclear 3 and an uneconomic 9.

I think parity is slightly more difficult to read, on balance. Say you lead the 4, fourth best, from a know 5-card suit. When you subsequently signal with the 6 it is clearly a high card since you are known to have a lower card (either the 3 or the 2). But it is not clear if the 6 is your only even spot (your low spot was 3) or the least even spot (you low spot was 2).

You could get around this by playing "4-th oddest leads" instead of 4th best Or maybe by playing Hi/Lo in the suit in which you made a 4th best lead but parity SP by his partner (and parity SP in suits in which you haven't lead a spot card).

[NickRW]

ahydra, on 2013-November-01, 08:24, said:

Personally I've found reverse attitude by far the most reliable (since it's safe most of the time to throw a high card in a suit you don't want, e.g. 9xx).

I agree,

[kenrexford]

helene_t, on 2013-November-01, 08:34, said:

You could get around this by playing "4-th oddest leads" instead of 4th best .

That agreement has been around for YEARS! You must be playing with some of my old partners. LOL

[Siegmund]

Quote

Why is this not done? Why have I not come across it?

The ACBL, among others, has banned them for 40-some years now.

The reasons are somewhat tenuous, in my opinion... there are a lot of interesting odd-even signaling ideas that people are reluctant to fully explore here because they can't play them anywhere except online. Maybe something marvelous will happen overseas and make people open their minds. (Or more likely they will ban it there too to even the playing field.)

[mycroft]

The reasons are not tenuous, but tarred with a broad brush. As in "I'm sure that there are some that can play this without tempo issues, and can play properly to the UI regulations when the odd failure happens, and I'm sure you are one of those. Unfortunately, the number who say they can, and the number who actually can, are two very different numbers."

If they're being honest and snarky instead of honest and diplomatic, they say the first sentence the same way. The second sentence is "Of course, you'd be the first..."

Back in Ontario, there were several pairs who played odd-even *signals*. I would suggest universally:

• they didn't know it was illegal;
  
• if called on it, they agreed with the TD, still played it during that round, and went back to playing it officially the next round;
  
• whether called on it or not (because I eventually stopped), it was obvious that they had much more trouble playing their least-even even card than their least-high high card; that as declarer, that information was very useful; and that opening leader's plays were consistent with an odd card having been played.

[Lorne50]

ahydra, on 2013-November-01, 08:24, said:

Personally I've found reverse attitude by far the most reliable (since it's safe most of the time to throw a high card in a suit you don't want, e.g. 9xx).

ahydra

Clearly the best in my opinion.

The trouble with many other systems is that every discard suggests partner does something when most of the time you want to discard something you do not need without suggesting anything and partner can then work out from his own hand what to do.

[fromageGB]

Tempo issues? If the intention is to give no signal, playing parity lavinthal with "the lower, the stronger the signal", I can't see how it is more difficult to play a high card than it is playing a middling card when playing magnitude lavinthal.

After my initial perusal of dummy I will have already worked out what cards I must keep in the form of guards, and what cards I may be able to easily spare, so when the time comes that a signal is needed, it will take no time to recognise a free card. I can't imagine it will take long to determine whether a card is odd or even.

I speak without experience : as it does not seem to be against regulations here, I am about to start playing this.