smerriman

Can't replicate it at a bidding table either - basic GIB responds with 2NT. Were you booted from the table during the hand at all? Since m1cha posted an example of that causing hands to change..

Since neither played reported anything, both were scored as a 'loss' of 5VP/20. This can't be changed now that round 7 is released.

http://webutil.bridgebase.com/v2/tview.php?t=ARDCHALLENGE:00a37d5e.3eaa.11e7.b134.0cc47a39aeb4-1495428553&u=smerriman smerriman 68 - ovncylmz 4 Having beaten me repeatedly in previous challenges, I finally had a challenge against Ovunc where his gambles didn't pay off :)

cherdano is actually correct; the other 5 days cherdano was waiting to find out whether to play olegru or icycookie, which was where the delay happened.

I'm not sure why you'd want to ask for aces, since with the heart and club situation, you're not going to have a clue what to do if partner replies with the very likely 2 - you may well lose 2 (or 3) club tricks before you know it. 4NT quantitative is standard; here you'd want to start with 3♥ which is an artificial, forcing, spade raise. You can then start cuebidding (after 4♣, 4♦, GIB will launch into Blackwood).

8 board playoffs.

spyrosm is using some software to generate the Swiss format but sent this 14 hours ago:

There's one at the bottom of here.

Without doing the calculations, the probability of dropping the queen is 57.92%, vs the finesse which is 56.22%. Thus the reason for the saying.

Knockouts here: http://www.bridgebase.com/forums/topic/76613-challenge-event-8a-knockouts-information-results/

Knockouts here: http://www.bridgebase.com/forums/topic/76613-challenge-event-8a-knockouts-information-results/

Results link (see Brackets tab): https://www.dropbox.com/s/v2m5a0iivxtx29f/Event%208A%20Q-RR-KO%20Fast.xlsx?dl=0 Please ensure you add your opponent as a friend before completing the first challenge in the set. Please complete this round by Thursday 11:59PM EST. GOLD BRACKET (4x16 boards, non-best hand, MP) pio_magic vs gordontd icycookie vs olegru ovncylmz vs nige1 m1cha vs sieong broze, artk78, nullve, and crazy4hoop all move directly to the quarterfinals, awaiting the winners of the above matches. Losers of the above matches will play in the silver bracket quarterfinals. SILVER BRACKET (3x16 boards, non-best hand, MP) natali_ vs cherdano wackojack vs impfdich linxu01 vs gerardo toast1 vs frank0

[hv=http://www.bridgebase.com/tools/handviewer.html?sn=smerriman&s=SKQHAKQ8732DA7CA7&wn=Robot&w=S9763H6DT9643CT82&nn=Robot&n=SAT82HT5DK5CQJ654&en=Robot&e=SJ54HJ94DQJ82CK93&d=s&v=o&b=27&a=2CP2D(2D%20bid%20waiting%20--%20forcing%20to%202N)P2H(Weak%20two%20bid%20--%206+%20%21H%3B%2010-%20HCP%3B%209+%20total)P3C!(Cheaper%20minor%20--%20forcing%20to%203H)P4H(6+%20%21H%3B%2024+%20total%20points)PPP&p=C2CQCKCAHAH6H5H4HKD3HTHJHQS7C4H9SKS3S2S4SQS6S8S5DAD6D5D8D7D4DKD2SASJC7S9C5C3H2CTH7D9C6C9H8C8CJDJH3DTSTDQ]400|300[/hv] How is the North hand worth a cheaper minor rebid only? And then not worth continuing over 4♥? Incidentally, putting this into a bidding table, GIB would bid the non-forcing 3♥ as South. North then uses Blackwood to reach 6♥. Edit - as another bug, I'm not sure why 2♥ was described as a weak 2 bid! But that's not relevant, since a bidding table results in the same cheaper minor bid (with the correct description for 2♥).

http://webutil.bridgebase.com/v2/tview.php?t=ARDCHALLENGE:635d7d3b.2fdd.11e7.b134.0cc47a39aeb4-1493801355&u=smerriman smerriman 5 - thelad 20

I monumentally stuffed up conceding 15 IMPs on board 9 with a novice mistake but somehow came away with a 12 IMP win smerriman 28 - xavierf 16 (+12) http://webutil.bridgebase.com/v2/tview.php?t=ARDCHALLENGE:9e551ac8.2e81.11e7.b134.0cc47a39aeb4-1493651990&u=smerriman

http://webutil.bridgebase.com/v2/tview.php?t=ARDCHALLENGE:4b4c9ed8.2f23.11e7.b134.0cc47a39aeb4-1493721429&u=smerriman smerriman 5.5 - mkgnao 4.5

The above was just for suit contracts where it definitely plays low from xxx (as per the system notes). I'm still trying to figure the exact 'normal' rules for NT - especially with regards to honor leads involving AK/AKQ - but while the system notes agree with you, preliminary analysis suggests they are plain wrong, GIB leads low from xxx against NT as well, which kind of ruins everything.

Alrighty, let's do some lead analysis! As well as looking at when GIB 'broke the rules' as to which card to lead, I used double dummy analysis to see how well this card compared to playing the 'normal' card of the same suit. This isn't perfect - for example, at IMPs, GIB may have simulated that a killing lead may defeat the contract enough times to make it worth it, even if that wasn't very often. Or, if not for its 'special' lead, it may have chosen to lead from another suit. And of course, simulations are telling it which suit to lead in the first place. However, I would still expect that if GIB is simulating correctly, the statistics should find GIB coming out on top when it decides to break the rules. For now I've just analysed suit contracts (will look at no trump independently later), and excluded cases of GIB leading a trump, as that's pretty special and I didn't have as much data there. (It generally seemed to follow the same rules, other than of course the rule about not underleading aces, but still with plenty of exceptions mixed in). The Rules In order of priority: 1) High from doubleton 2) K from AK+ 3) A from A high 4) Top of sequence of 2 from KQ+ down to T9+ (it treats 10 as an honour here) 5) Top of interior sequence of 2 (JT or T9) 6) Low from trebleton 7) Fourth high All of these rules generally appear to apply when leading trumps as well, except as expected it skips the rule for leading A from A high. Since of course I don't have anywhere near as much data for leading trumps as non-trumps, I'll exclude trump leads from the analysis below (but similar exceptions pop up). Now, let's see how well it performed. 1) High from doubleton GIB had a touching doubleton on 603 occasions and always led high. However, when the doubleton wasn't touching, in 79 out of 2379 hands (3.3%) when leading from non-touching doubletons, it lead low. This including occasionally underleading an Ace (of the 199 occasions it lead from A8 or worse, 7 times it underled the Ace), with absolutely no logical reason to do so on the ones I checked: low from A7, when Ace would defeat the contract low from A8 - luckily didn't cost on this occasion, but surely would a lot of the time given this bidding/distribution low from A2, again I can easily see it costing a trick especially given this bidding, but never gaining. It occasionally lead low from other honours, and perhaps somewhere amongst the list there is an example or two where there is a reason for doing so. However, good luck coming up with a simulation-based excuse for leading low from 64, 74, 83, 73, and 84. How did these leads work out for GIB from a double dummy perspective? In 72 of the 79 occasions, the 'normal' card achieved the same double dummy score as the card GIB played. On 7 occasions, GIB's card was *worse*. On 0 occasions was GIB's card better. Score: GIB 0 - Rules 7 2) K from AK+ GIB played the K on 1061/1061 occasions. Whew. Though, given the other results, I kind of find this surprising. Score: GIB 0 - Rules 0 3) A from A high Excluding doubletons and holding AK, of the other 1143 times GIB lead from a suit with an Ace, it underled the Ace on 238 occasions (21%). Many of these are ludicrous, such as this one. GIB seems to have a penchant for leading low from weak aces. When leading from Axx, GIB underled the Ace on 70/182 occasions (38.5%). Using double dummy results compared to the Ace, it didn't work out well - on 52 occasions it didn't matter; it gained on 2 hands, but lost on 16. When leading from Axxx, GIB underled the Ace on 52/190 occasions (27.4%). Dummy double results were a bit closer, but still in favour of the Ace: +6, =35, -11. It achieved similar results for some other hands, but still at a loss. Score: GIB 19 - Rules 48. 4) Top of sequence of 2 GIB led from a suit headed by KQ+ down to T9+ on 2480 occasions. On 38 of these (1.5%) it played low. Most of these fit no pattern, though GIB did lead low from JTxx on 8/220 occasions. As usual, some of the rest simply made no sense, such as this one . Score: GIB 2 - Rules 7. 5) Top of interior sequence of 2 When the normal lead would have been top of an interior sequence, GIB decided to go against the trend on 12/213 occasions (5.6%). On 4 occasions it played an unsupported king from a suit headed KJT - double dummy comparisons showed this didn't cost on any of the occasions, though it didn't gain either. The other 8 involved it playing small - costing it a trick on one occasion. Score: GIB 0 - Rules 1. 6) Low from trebleton On 1936 occasions, GIB had a trebleton where the normal card was to play low. GIB ignored this on 44 occasions (2.3%). On these occasions it decided to lead an unsupported honour (or occasionally a 9 from J9x or 9xx). On none of these did GIB gain a trick. Score: GIB 0 - Rules 3. 7) Fourth high On 2270 occasions, GIB was meant to play fourth high. It played something else on 59 occasions (2.6%) - never gaining a trick. Can a simulation really tell GIB that it's much better off leading 5 from QT875 in a side suit? Score: GIB 0 - Rules 5. Overall summary Over 12164 hands, GIB 'broke the rules' on 470 occasions. Half of these were due to it deciding to underlead an ace. Compared with leading the ace, this gained a trick 19 times, but cost a trick 48 times. The other half came from an assortment of other situations. Compared with the 'normal' card from the same suit, only twice did this gain a trick - while it cost a trick on 23 occasions. Final score: GIB 21 - Rules 71.

Interesting - I thought #1 that was basically ruled out as impossible (not quite sure what you mean by 2). Can you provide a couple of demo hands to make sure I'm understanding what you're suggesting - I can see if the hands I have prove otherwise.

I could so - what sort of info would you be interested in? Unlike GIB's signals which are clearly buggy, I tend to trust its lead algorithm is accurate, even though assuming partner plays double dummy isn't always a great assumption. But I guess one thing that comes to mind is, say, the probability GIB has an honor when leading small against 3NT, or something like that. (AKA, why all finesses on the opening lead fail.)

Why is that a problem? I'd just bid 5♣ and expect to be making easily. In that situation, we seem to be in a much better position than had we overcalled 2♣ followed by a 4♥ jump, when partner is likely to be passing hands where even 6♣ is cold.

Yes there is. Your 2♥ bid was a mistake - you should bid 2nt instead. Since you didn't bid 2nt, you must have an unbalanced hand, thus the reason 3♥ shows 6 hearts and thus the reason GIB thought 3nt wasn't a sensible final contract.

Here's the correct link. http://webutil.bridgebase.com/v2/tview.php?t=ARDCHALLENGE:583fa6f9.279b.11e7.b134.0cc47a39aeb4-1492893381&u=smerriman

The GIB System Notes page is very clear how GIB follows to an opening lead: Anyone who has played with GIB knows it doesn't quite work like this. Barmar's take on things:

Yep.