Odds Question
#1
Posted 2008-November-09, 09:20
Here's the question: Suits fall in one of two parities (I am dealt either three odd-numbered suits and one even-numbered suit OR three even-numbered suits and one odd. So, if I discover the nature of one of the suits, do the odds favor a different suit being of the ame nature? In other words, if LHO has three spades, do the odds favor him also having an odd number of hearts?
The math seems to suggest that the answer is no.
If spades are odd, then the "odds" are roughly 75% that this person has three odds and an even, right? When that is accurate, then 2/3 of the remaining suits will be odd. However, I only have a 75% reliability to the assumption that 2/3 of the suits will be odd. 3/4 of 2/3 is 6/12, or 50-50.
How about the opposite? 25% of the time, spades, if odd, will be the only odd suit. When that happens, all of the other suits will be even. That's 1/4. However, I have a large unreliability factor on the "it is the opposite" hypo, with 75% of the time this thesis failing, except that the false thesis will work 1/3 of that failed time. 3/4 of 1/3 is 3/12, or 1/4. 1/4+1/4=1/2. Same 50-50 scenario.
Knowing two suits does me no better.
What if I know one suit and need to then know if two suits will both behave in the same manner? 25% of the time, they will assuredly, because the known is the odd-man-out. When the known is one of three, 75% of the time, then the odds of the other two both being the same type are one in three. 3/4 of 1/3 is that stupid 1/4. 1/4+1/4=1/2.
Am I missing something, or does knowledge in this area ever give any odds advantage? Obviously, three knowns yield a known, but can any lesser knowledge help here? Also obviously two knowns yield a "known" of sorts (two matches yield two non-matches, but two non-matches yield a match), but these are always 100% knowns.
-P.J. Painter.
#2
Posted 2008-November-09, 10:28
You know your hands shape and dummies shape, if you additionally know something about LHO or RHO's length in one suit you can combine those informations, did you take that into account?
#3
Posted 2008-November-09, 11:00
If we know the spade distrubution and want to calculate odds about the heart distribution, then all the minor cards are 'equals'.
In a sense, it's just random that we call the 13 diamonds a suit and the 13 clubs a suit. Imagine a different game with 5 suits. Spades, hearts, diamonds, club 2-9, club honours. In this game with 5 suits, we would have a different hand pattern with odd/even parity hands. But surely your problem with the heart distribution is the same. The solution of this problem cannot depend on how we arbitrarily have defined the concept "suit".
In other words, the complexity of this problem only allow us to focus on three types of cards:
1 - cards that we can place for sure (here: spades)
2 - cards that we cannot place (here: the minors)
3 - cards that we want to make calculations about (here: hearts)
Splitting up category 2 is not giving us any extra information.
#4
Posted 2008-November-09, 12:01
You have 13 cards in each hand. If you know how many cards are in one suit, then you know how many cards are in the remaining 3 suits. The number of cards must add up to 13. Everything else follows from that.
It really is no more complicated than that.
#5
Posted 2008-November-09, 12:07
MFA, on Nov 9 2008, 12:00 PM, said:
If we know the spade distrubution and want to calculate odds about the heart distribution, then all the minor cards are 'equals'.
In a sense, it's just random that we call the 13 diamonds a suit and the 13 clubs a suit. Imagine a different game with 5 suits. Spades, hearts, diamonds, club 2-9, club honours. In this game with 5 suits, we would have a different hand pattern with odd/even parity hands. But surely your problem with the heart distribution is the same. The solution of this problem cannot depend on how we arbitrarily have defined the concept "suit".
In other words, the complexity of this problem only allow us to focus on three types of cards:
1 - cards that we can place for sure (here: spades)
2 - cards that we cannot place (here: the minors)
3 - cards that we want to make calculations about (here: hearts)
Splitting up category 2 is not giving us any extra information.
That makes a lot of sense.
-P.J. Painter.
#6
Posted 2008-November-09, 12:14
You don't need to use the signals to benefit from the theory.
Harald
#7
Posted 2008-November-09, 17:02
skaeran, on Nov 9 2008, 01:14 PM, said:
You don't need to use the signals to benefit from the theory.
I have known about prism signals from Vinje back when I heard about it when the first George Bush was president. I never have understood why this is deemed "encrypted." But, that was the source of my question.
-P.J. Painter.
#8
Posted 2008-November-09, 17:46
It turns out that if you see:
0, 1, 4, 5, 6, 10, 11, 12, 13 (trivially) spades then you are more likely to have an even number of hearts
and
2, 3, 7, 8, 9 spades then you are more likely to have an odd number of hearts.
This seems to suggest that if you see:
0, 4, 6, 10, 12 spades then the hand is more likely to have three even suits
3, 7, 9 spades then the hand is more likely to have three odd suits.
If you know two suits and the total is even then it is exactly 50-50 whether a third suit is even or odd.
If the total is 1, 5, 9, 13 then you are more likely to be even for the other suits.
3, 7, 11 then you are more likely to be odd for the other suits.
Here are the numbers for the number of hearts given each number of spades:
No Spades 0 0.00128048 1 0.015457218 2 0.074194646 3 0.187032337 4 0.275047554 5 0.247542798 6 0.138971396 7 0.048639988 8 0.010422855 9 0.001316017 10 9.1549E-05 11 3.12099E-06 12 4.16132E-08 13 1.23116E-10 Even 0.50000852 Odd 0.49999148 One Spade 0 0.002469496 1 0.025682762 2 0.105941393 3 0.228501045 4 0.285626306 5 0.216474674 6 0.101021515 7 0.02886329 8 0.004919879 9 0.000475351 10 2.37675E-05 11 5.18564E-07 12 3.32413E-09 Even 0.50000236 Odd 0.49999764 Two Spades 0 0.004609727 1 0.041199431 2 0.145409756 3 0.266584552 4 0.280615318 5 0.17678765 6 0.067347676 7 0.01530629 8 0.001996473 9 0.000138644 10 4.43661E-06 11 4.65378E-08 Even 0.499983386 Odd 0.500016614 Three Spades 0 0.008355129 1 0.063892165 2 0.191676496 3 0.295921608 4 0.258931407 5 0.133164724 6 0.040352947 7 0.007017904 8 0.000657928 9 2.92413E-05 10 4.49866E-07 Even 0.499974358 Odd 0.500025642 Four Spades 0 0.014744346 1 0.095838248 2 0.242117679 3 0.310717689 4 0.221941206 5 0.09079413 6 0.021053711 7 0.002631714 8 0.000157903 9 3.37399E-06 Even 0.500014846 Odd 0.499985154 Five Spades 0 0.02539304 1 0.138993483 2 0.291886314 3 0.305785662 4 0.173741853 5 0.054388754 6 0.009064792 7 0.000725183 8 2.09188E-05 Even 0.500106918 Odd 0.499893082 Six Spades 0 0.042767225 1 0.194590876 2 0.333584358 3 0.277986965 4 0.120863898 5 0.027194377 6 0.002900734 7 0.000111567 Even 0.500116215 Odd 0.499883785 Seven Spades 0 0.070565922 1 0.262101996 2 0.357411813 3 0.227914779 4 0.071223368 5 0.010256165 6 0.000525957 Even 0.49972706 Odd 0.50027294 Eight Spades 0 0.114249588 1 0.337555601 2 0.352231931 3 0.161439635 4 0.032287927 5 0.002235318 Even 0.498769446 Odd 0.501230554 Nine Spades 0 0.181760708 1 0.410937253 2 0.30820294 3 0.090406196 4 0.008692903 Even 0.498656551 Odd 0.501343449 Ten Spades 0 0.284495021 1 0.46230441 2 0.221906117 3 0.031294452 Even 0.506401138 Odd 0.493598862 Eleven Spades 0 0.438596491 1 0.456140351 2 0.105263158 Even 0.543859649 Odd 0.456140351 Twelve Spades 0 0.666666667 1 0.333333333 Even 0.666666667 Odd 0.333333333 Thirteen Spades 0 1 Even 1 Odd 0
I believe that the USA currently hold only the World Championship For People Who Still Bid Like Your Auntie Gladys - dburn
dunno how to play 4 card majors - JLOGIC
True but I know Standard American and what better reason could I have for playing Precision? - Hideous Hog
Bidding is an estimation of probabilities SJ Simon
#9
Posted 2008-November-09, 18:08
kenrexford, on Nov 9 2008, 03:02 PM, said:
skaeran, on Nov 9 2008, 01:14 PM, said:
You don't need to use the signals to benefit from the theory.
I have known about prism signals from Vinje back when I heard about it when the first George Bush was president. I never have understood why this is deemed "encrypted." But, that was the source of my question.
I got the Vinje book when Reagan was Prez. His 1st term

It is bizarre now as it was then. As a new player, I had no idea how complicated this game was. When I was reading it, all I could think was ".....wow, I'm just NOT getting this".
#10
Posted 2008-November-09, 19:24
kenrexford, on Nov 9 2008, 06:02 PM, said:
I don't think these are encrypted. Encryption implies the presence of a key permitting the message to be unscrambled. Pattern-type signaling methods should be thought of as a different coding scheme. Instead of sending, for example, for a count-happy pair:
true -> even number of spades and then
false-> odd number of hearts
you send (count hearts) ^ (count spades). Later you send either count(hearts), or you send count(spades) -- it does not matter -- allowing the first message to be decoded.
It seems, at least if you believe the Vinje and Prism claims, that Prism is a more efficient coding scheme than sending count of the suits over one by one. My understanding of why this is is that you frequently have some information about declarer's hand pattern from the auction and when you factor this information in, you can count out more hands after only one signal.
The GCC says something about "mumble, mumble, only right-side-up or upside-down coding schemes, mumble mumble." I don't see why this prohibits pattern-type signaling methods as long as high-low ALWAYS means "odd pattern" or always means "even pattern."
This does not mean that your local cop^H TD won't enforce the rules to his liking, however.
#11
Posted 2008-November-09, 19:38
pclayton, on Nov 9 2008, 07:08 PM, said:
kenrexford, on Nov 9 2008, 03:02 PM, said:
skaeran, on Nov 9 2008, 01:14 PM, said:
You don't need to use the signals to benefit from the theory.
I have known about prism signals from Vinje back when I heard about it when the first George Bush was president. I never have understood why this is deemed "encrypted." But, that was the source of my question.
I got the Vinje book when Reagan was Prez. His 1st term

It is bizarre now as it was then. As a new player, I had no idea how complicated this game was. When I was reading it, all I could think was ".....wow, I'm just NOT getting this".
You're an old fart!

-P.J. Painter.
#12
Posted 2008-November-10, 12:35
kenrexford, on Nov 10 2008, 03:38 AM, said:
pclayton, on Nov 9 2008, 07:08 PM, said:
kenrexford, on Nov 9 2008, 03:02 PM, said:
skaeran, on Nov 9 2008, 01:14 PM, said:
You don't need to use the signals to benefit from the theory.
I have known about prism signals from Vinje back when I heard about it when the first George Bush was president. I never have understood why this is deemed "encrypted." But, that was the source of my question.
I got the Vinje book when Reagan was Prez. His 1st term

It is bizarre now as it was then. As a new player, I had no idea how complicated this game was. When I was reading it, all I could think was ".....wow, I'm just NOT getting this".
You're an old fart!

Damn you Ken, you're insulting me. I got the Norwegian original book earlier (it was published in 1976).

Harald
#13
Posted 2008-November-10, 18:34
-P.J. Painter.
#14
Posted 2008-November-10, 20:10
Sean