I was playing at a local casino and noticed a dealer completly flashing a hold card almost every time- i ran to the bank pulled out most of my roll and headed back as fast as I could- sat down bought in table max of 2500 and lost the first 6 hands in a row while seeing her card , im so sick right now

first three hand got 18 19 and 19 in blackjack 20 and 20- didnt hit even thuogh it killed me, and didnt surrender so I didnt blow cover

fourht hand 83 vs 6 with a 9 in the hold double pull a 8 dealer gets 20

fifth hand 66 into a 5 and ten underneath, split get a 5 double get 4 second 6 get a 3 double pull a7 dealer gets 18 next two hands 17 into an 18 and 16 into a 6- with four underneath, hit got a ten didnt matter- next hand dealer blackjack and hnestly forget the rest, how to lose 25k in 10 minutes

Depends on how much cover you use. Theoretically, you can have a 13% advantage. But most practically, it is around 10%.Quote:strictlyAPanyone know what the ev is when seeing the dealers hold card in bj?

the extreme short term its the toy of variance, as

you just found out.

Quote:strictlyAPanyone know what the ev is when seeing the dealers hold card in bj?

Considering "Double Exposure" BJ variant, probably not much more than 10%. And since you were trying to stay covered, it's likely less than 10%. Sorry about your loss.

https://wizardofodds.com/games/double-exposure/

https://wizardofodds.com/games/blackjack/rule-variations/

Quote:WizardYou should have bet about 10% of your BR per hand. Maybe you overbet it, but it was a good bet.

Don't forget to resize your bets! When betting with a small edge you can get away with resizing on a per-buy-in or per-sessions basis, but if you are really betting 10% you need to resize every single hand.

Furthermore, if the edge is 10%, then 10% of BR is an overbet. Don't forget to divide the edge by the variance to get the correct Kelly number. I'm not sure, off the top of my head, what the variance of a single hand is when hole-carding but it's got to be fairly high (I'd assume that you are splitting and doubling more often). Off the top of my head I'd guess that with a 10% edge, the right bet is closer to 6 or 7 % of bankroll.

Also, when betting this much of your BR, you need to make risk-averse plays. It is absolutely not correct to split or double in close situations with a bet that large. Honestly, it is going to be very difficult to figure out a correct strategy on the fly -- controlling variance becomes much more important than maximizing EV when you have that large of a percentage of your BR on the line and multiple correlated bets (through splits/doubles, or playing multiple hands).

I'd probably just spread to 3 hands with 1.5 to 2% of my BR on each hand, not make risk-averse plays, and resize bets fairly frequently (whenever it's comfortable to do so with the chip size being used). This is obviously not optimal, but, without time to run simulations, I'd suspect that this would perform fairly well, and it gets rid of the requirement to make difficult calculations at the table.

Quote:sodawaterIt's not like he was going to be able to play with this star dealer every day or any guarantee she would keep flashing the hole card. So I don't think Kelly betting really applies here. I think taking a huge shot with as much of your bankroll as you can muster with a ~10% edge that could disappear at any time is the best way to play it.

No, it still applies. Assuming you can continue to get some more advantage plays in the future (not necessarily this one, not necessarily with the same edge) the way to maximize your long term bankroll growth is to maximize the expectation of the log of your BR at every decision.

Quote:AxiomOfChoiceNo, it still applies. Assuming you can continue to get some more advantage plays in the future (not necessarily this one, not necessarily with the same edge) the way to maximize your long term bankroll growth is to maximize the expectation of the log of your BR at every decision.

yeah that makes sense.

Hold it right there. You noticed a dealer was flashing his hole card. Did you notice if anyone was winning or not. Right there you have the crux of the matter. You thought you could jump in and start winning because you go around looking for hole card flashers and take advantage of them when you find them.Quote:strictlyAPI was playing at a local casino and noticed a dealer completely flashing a hold card almost every time-

Stop. notice the table limits, notice the other players, are they blind or do they see a hole card and still lose? Just as Basic Strategy does not guarantee you a "win", it just constitutes "optimal play". so too is "Basic Strategy Enhanced by Hole Card Knowledge" simply "super optimal play" but not a guaranteed win.

Note: Once you are losing your shirt, you don't need any "cover".

Makes no difference if two suits discussing you say "he be jerk who lost 25 grand" or say "he be card-counting jerk who lost 25 grand".

Quote:IbeatyouracesOverbetting is the biggest downfall of advantage gamblers. They falsely believe that because they have an edge that they simply cannot lose.

Yup. the Godfather of gambling is variance. It can

and will screw with you without warning. Bring you

to your knees crying like a newborn baby. Always

keep it in mind. Design everything you do around

it. This falls under the category of wising up chumps,

and I expect it to be mostly ignored. As usual.

Quote:sodawaterSo I don't think Kelly betting really applies here.

Correct and not quite simultaneously.

If you had a 100% edge - that's easy, 100x payout on 2% odds event - would you bet 100% of your bankroll?

Kelly Criterion applies well to small advantages. At large advantage, you need to bet less than that.

A key factor here would be risk of ruin and time to play. You'd need to size your bets to accommodate moderate risk of ruin through available play time.

Quote:P90Correct and not quite simultaneously.

If you had a 100% edge - that's easy, 100x payout on 2% odds event - would you bet 100% of your bankroll?

No, and that's not what the Kelly Criterion says to bet.

http://en.wikipedia.org/wiki/Kelly_criterion

The often quoted "edge times your bankroll" is only correct for even money bets.

For your example, your EV per dollar bet is $51/50 = $1.02 (ie, your edge is 102%), so you would bet $1.02/$100 = 1.02% of your bankroll for maximal long-term bankroll growth.

The situation, as I view it, is that the player had inside knowledge -- he saw a card flashed which helped him make a decision about his play.

But a more important quesiton is this and I wonder if the original poster will comment: when you saw the card were you able to judge just how much it helped your particular hand?

And in blackjack, couldnt that knowledge of the dealer's card be meaningless if you, yourself, are holding weak cards not helped by the flashed card?

And now a general question: does this (what I will call) inside information always help by the 10% or 13% margin you are all discussing, or is that an average and reflects the particular cards in your hand that you are playing?

Now, let me just take this outside of the casino for a moment and make a "outside the casino comparison."

Suppose you are a stock speculator and you had inside information that Company A was having a problem with its production lines. While you might have that inside information you would still have to decide if such information would affect the company's stock. Further investigation might tell you that the company is now in production hiatus for three months and that gives the company plenty of time to fix the problem.

Now taking this to the blackjack table, the analogy is, the player might know what the flashed card is, but looking at his own hand can he say it will improve his chances?

Again, I know nothing about blackjack but I wonder if this reasoning applies. thanks.

Quote:AxiomOfChoiceThe often quoted "edge times your bankroll" is only correct for even money bets.

Right, forgot that. Regardless, beside the point.

Kelly Criterion is not the best amount to bet under all and any circumstances. More specifically, KC is the amount to obtain the highest average gain in a game with a fixed number of trials, PA=const, free bet size change on every trial, maximum win (house bankroll)=infinity.

For some games with small PA, the situation is well approximated by the above. When PA is high, it's not, since the number of trials is no longer fixed, betting is not unrestricted, and maximum win (at which PA is not taken away) is not infinity.

If any of the above is not met, optimum bet changes. For instance, if you can not reduce bet size below the first bet, or can not increase it above, or bet size is highly granular, then optimal bet != KC. If the game continues until a fixed win or loss amount, then optimal bet size != KC.

Generally, with high PA, here or elsewhere, target RoR is more relevant to bet sizing than KC. Strictly KC betting with casual-looking bet sizing will give you a higher chance of taking money that doesn't exist [won't be made available to you] at the expense of a lower chance of reaching target win rate or win amount.

'

As far as Kelly, which I am no great fan of, shouldn't the bets have been scaled down as your bankroll decreased ?

This did not sound like AP to me. More like trying to get rich FAST.

HERE GOES NOTHING _________________________________________________- ill try and update from bathroom in between dealers

Quote:IbeatyouracesGoing back to the original post and rereading the hands dealt, it looks to me that even though he knew the HC, except in the last hand (16 vs 6 up 4 in hole) he pretty much had to follow standard BS whether he knew the HC or not.

And you'd be a fool to hit 17 or higher even though against a pat dealer 20.

id hit 89 but not T7. hitting 89 could be an honest mistake misreading your hand.

Quote:IbeatyouracesAnd you'd be a fool to hit 17 or higher even though against a pat dealer 20.

I disagree - if you know the hole card, and trying to make a quick getaway with a big win, why not hit it - cover be damned? Otherwise, you are guaranteed a loss.

Quote:strictlyAPtried to keep cover, its a small casino and ill discuss later why no one noticed , but I am heading back right now, shift started and she is there - I had to take money out of a non bankroll situation . Wish me luck- I am going with the wizards theory a good bet is a good bet, It probably not a 10 percent edge because unless I am up right away big money where I can walk away if they cut it, I would probably not hit 15's into a 6 with and ace underneath so just not to blow it from weird play- however if I am up then yes split 77 in a ten showing if there is a 6 underneath-

HERE GOES NOTHING _________________________________________________- ill try and update from bathroom in between dealers

May Lady Variance bless you with her charms.

You sir, are my new hero!!! Go for it and please update ASAP!

Quote:IbeatyouracesI'll take longevity over a quick score any day. This is why we make cover plays. Milk the cow, don't slaughter it. You'll learn this as you gain more experience. We don't even hit A,8 vs a 20.

But, in the scenario AP is in, it is not known if the hole card flashing will go on for any length of time - that is whY I would recommend burning the proverbial bridge of this casino

Quote:strictlyAPtried to keep cover, its a small casino and ill discuss later why no one noticed , but I am heading back right now, shift started and she is there - I had to take money out of a non bankroll situation . Wish me luck- I am going with the wizards theory a good bet is a good bet, It probably not a 10 percent edge because unless I am up right away big money where I can walk away if they cut it, I would probably not hit 15's into a 6 with and ace underneath so just not to blow it from weird play- however if I am up then yes split 77 in a ten showing if there is a 6 underneath-

HERE GOES NOTHING _________________________________________________- ill try and update from bathroom in between dealers

Now that you know your edge, if things go south again, please reduce your unit size (gigiddy) per the Kelly criterion. Like ibeatyouraces says, longevity is the key.

Quote:IbeatyouracesSure you never know how long it will last but why make it obvious and possibly ruin it now? We still play dealers we found out years ago because we don't over expose ourselves.

BUt, if the whole reason you are playing is due to the flashed hole card - and you do not use that to your advantage - why even bother to rush to the bank to get money to play with a dealer who flashes the hole card? Isn't the idea to get in while the gettin's good?

Quote:aceofspadesBUt, if the whole reason you are playing is due to the flashed hole card - and you do not use that to your advantage - why even bother to rush to the bank to get money to play with a dealer who flashes the hole card? Isn't the idea to get in while the gettin's good?

Why not do some social engineering, and find out when that particular dealer usually comes on shift? Works good, especially if you are a local or live close by.

Quote:aceofspadesBUt, if the whole reason you are playing is due to the flashed hole card - and you do not use that to your advantage - why even bother to rush to the bank to get money to play with a dealer who flashes the hole card? Isn't the idea to get in while the gettin's good?

Depends on how you look at it. On the one hand, if the dealer is as bad as advertised she won't last long so the player may as well go all-out. On the other hand, it's better to make 5%/hand for 10,000 hands than 10% for 100 hands.

Quote:P90Kelly Criterion is not the best amount to bet under all and any circumstances. More specifically, KC is the amount to obtain the highest average gain in a game with a fixed number of trials, PA=const, free bet size change on every trial, maximum win (house bankroll)=infinity.

Actually, no. The Kelly criterion does NOT assume a fixed number of trials. Just the opposite; it assumes infinitely many trials. In particular, it assumes that you can always get another bet later. It does not assume the player advantage to be constant (obviously if your advantage changes from trial to trial so does your bet size). In other words, if you have a game with a 10% edge, you should bet according to the Kelly criterion until that dries up (including the very last bet). If another game pops up, with a different edge, then you can play that one, also sizing your bets according to Kelly. The only time it falls apart is if you are in a situation where you will never get to make another bet again.

Quote:

For some games with small PA, the situation is well approximated by the above. When PA is high, it's not, since the number of trials is no longer fixed, betting is not unrestricted, and maximum win (at which PA is not taken away) is not infinity.

This is incorrect. Bet size need not be unrestricted. I'm not sure why you think this.

The Kelly Criterion can be generally stated as: In order to maximize long-term bankroll growth (ie, growth over many trials), then, at each individual trial you should maximize the expectation of the log of the of your bankroll.

If there is a limit on the amount you can wager (eg, a minimum or maximum bet) then you maximize the expectation of the log of your bankroll within the restrictions presented to you. It's the optimal choice among the ones you have available to you.

Quote:

If any of the above is not met, optimum bet changes. For instance, if you can not reduce bet size below the first bet, or can not increase it above, or bet size is highly granular, then optimal bet != KC. If the game continues until a fixed win or loss amount, then optimal bet size != KC.

In its general form, the Kelly Criterion simply provides a way of comparing various choices. The "value" of a bet size is the expectation of the log of your bankroll after the bet. Out of all your options, you just choose the one with the highest value. There might be a bet size that would have even higher value, but, if that's not one of your choices, it's not one of your choices. All you can do is pick the best one available to you.

Quote:Generally, with high PA, here or elsewhere, target RoR is more relevant to bet sizing than KC. Strictly KC betting with casual-looking bet sizing will give you a higher chance of taking money that doesn't exist [won't be made available to you] at the expense of a lower chance of reaching target win rate or win amount.

I've heard other people say that before, but it's not true. Kelly Criterion will grow your bankroll more quickly, which will get you to the point where the max bet available to you is the one with the most value (ie, has the highest expectation of the log of your bankroll out of all your choices). In other words, you get to the point where you are betting table max more quickly, which leads you to making more money.

Quote:treetopbuddyOnce you realized the dealer was showing the hole card you should have immediately alerted the pit boss. It's just not fair for you to have a 6-10% advantage over the house. You were cheating and Karma came down on you.....just kidding.....trying a little humor to dull pain. I've been there. Sorry for your loss (sound like funeral director)

lol... good one

secondly, the Wizard says "advantage/variance" is the rule of thumb, not "HE times bankroll"

Quote:odiousgambitsecondly, the Wizard says "advantage/variance" is the rule of thumb, not "HE times bankroll"

This is true, but even that falls apart for blackjack. You can lower your variance by making sub-optimal (in terms of EV) plays -- aka risk-averse plays (not doubling or splitting in close situations). Even though these don't maximize EV (the expectation of your bankroll) they may very well maximize the expectation of the log of your bankroll, which is the goal.

Unfortunately, figuring out which plays to actually make requires knowing the EV of each play (not just which play is the best), and being able to do a fairly complex calculation in your head on the fly (and it changes depending how big your bet was as a % of your BR). I don't think that this is particularly realistic. That's why I'd recommend betting somewhat less and avoiding risk-averse plays.

Even if you could play perfectly optimally (optimizing E(log(BR))), it would still make the bet size calculation somewhat difficult, since, the more you bet, the more risk-averse plays you have to make, which lowers your edge. In other words, higher bets have lower edges. Solving this problem completely is not easy -- I'm not sure if it has ever been done.

Quote:AxiomOfChoiceActually, no. The Kelly criterion does NOT assume a fixed number of trials. Just the opposite; it assumes infinitely many trials. In particular, it assumes that you can always get another bet later.

I didn't say it assumes any fixed number of trials. Rather that's it produces optimal results with a fixed number of trials.

If the number of trials is unlimited, betting according to KC would be erroneous.

Do I need to explain why, or is it obvious enough?

I probably need. If the number of trials is unlimited, it means something else is the limit. In high PA situations, the limit can be either the maximum win or the maximum win rate. For instance, you need to win $X; you can not win more, because [select reason:] the opponent will run out of money; the opponent will sweat the money; the hole will be plugged.

With an unlimited number of trials, growth rate or any other rate is of zero significance, only end outcome probabilities are of significance. So the best amount to bet would be one with the highest chance to win, and therefore the smallest amount you are allowed to bet.

This is not a purely theoretical situation. It's not even unseen; a multi-line video poker machine provides it. If given e.g. a machine with unlimited lines or a hack that can auto-play perfect strategy for you, the correct bet would always be the minimum (that does not reduce the relative payout) while maximizing the number of trials.

It's not that Kelly Criterion isn't the best way of maximizing the metric which it's intended to maximize under the conditions which it applies to. It is best at that. Rather it's the metric KC is designed to maximize that is, put bluntly, relatively unimportant in most practical scenarios, and the conditions of applicability that are never fully met and only sometimes approximated.

Quote:AxiomOfChoiceI've heard other people say that before, but it's not true. Kelly Criterion will grow your bankroll more quickly, which will get you to the point where the max bet available to you is the one with the most value (ie, has the highest expectation of the log of your bankroll out of all your choices). In other words, you get to the point where you are betting table max more quickly, which leads you to making more money.

You may have heard them say it for a reason, then, just assumed they must have been wrong because they didn't agree with you.

In this example, such a suggestion is actually erroneous, not just a semantic difference. Sizing the bet unit at KC without the ability to infinitely resize it at will assume a high risk of ruin. If you bust out - lose your bankroll - your win rate will be $0/hour.

Sizing it at KC will maximize how fast you get there, if you get there, at the expense of a lower chance of getting there. With a large number of trials, the post-bust win rate of $0/hour won't be compensated for by a few more trials at maximum bet when not busting. Resulting in a lower average (and much lower log average) and making this incorrect bet sizing.

"Without the ability to infinitely resize it at will" is not a hypothetical scenario either. In any multi-betting game - poker variants, blackjack - follow-up bets are fixed at initial bet size; they can not be resized at will. Betting 13% you will commonly place 52% on the table with a split and doubles, and sometimes more. The first bet was correct; all others weren't.

The answer is then RoR sizing of the basic betting unit and fractional-KC sizing of bets when well above granularity or betting minimum imposed limits.

You are guaranteed a loss on that hand but you want to preserve the game.Using some cover this game might last for a while,why kill it in one day?Would you hit 19 against a 20?Quote:aceofspadesI disagree - if you know the hole card, and trying to make a quick getaway with a big win, why not hit it - cover be damned? Otherwise, you are guaranteed a loss.

Quote:HunterhillYou are guaranteed a loss on that hand but you want to preserve the game.Using some cover this game might last for a while,why kill it in one day?Would you hit 19 against a 20?

If I had $5k up and knew I was going to lose it - yeah I would hit it

Quote:Mission146You would anticipate getting all that back and more by not hitting it if you can keep that game going.

But, as we saw - the game can go on indefinitely, but the bankroll does not...

Thats because he was overbetting his bankroll.Would you rather win that one 5k bet or win many 1000 dollar bets.I had a game that lasted for 3 years, then some bozo hit hard 18 surrendered a hard 19 and killed the game in 10 minutes.I know this because I was waiting to get the seat and saw these 2 plays happen. I left the area right away,came back later and the game was no more.People need to think of the long run.Quote:aceofspadesBut, as we saw - the game can go on indefinitely, but the bankroll does not...

Quote:HunterhillI had a game that lasted for 3 years, then some bozo hit hard 18 surrendered a hard 19 and killed the game in 10 minutes.I know this because I was waiting to get the seat and saw these 2 plays happen.

It's probably the surrender more than the hit that did it... I've seen some interesting moves before: Standing a 7, hitting a soft 20, splitting 99 with a dealer 7... even trying to hit a soft 21, but the dealer automatically moved onto the next person before checking if they wanted to stand. Never a boneheaded surrender though. People that surrender tend to know what they're doing.

Still, pity to lose a winning spot.

Quote:BuzzardI am math illiterate. Seems to me this is like having a jar with 55 black marbles and 45 white marbles ? Not the greatest edge in the world. Especially when some white marbles can cause you to lose 2 or 3 times your bet with splits and Doubles. Going at that with a betting scheme that says if you are 10 bets down at any point in time, your ass is cooked !

'

As far as Kelly, which I am no great fan of, shouldn't the bets have been scaled down as your bankroll decreased ?

This did not sound like AP to me. More like trying to get rich FAST.

To use your example an on Average a BJ Counter plays with an Advantage of 50.5 black marbles against 49.5 white marbles (ie 1% edge)

When the Count is +5 (thats's the usual highest Count he sees at a few % of hands) where he maxes his bet he plays with 51 black marbles against 49 white marbles (2% edge).

If he gets as you say 55 black marbles against 45 white marbles (10% edge) at an almost Even payout game (variance of around 1.3) he more or less bets the house. It does not sound much to an average gambler because of the inability to grasp what a 10% edge on an even game means.

And this is exaclty what an Ap does.

As other people mentioned on an Even payout game you bet the % of Advanthe on your Payroll.

On BJ you divide this by this 1.3 Variance (this is an approximation to the optimum bet).

So for $100.000 Payroll you Bet 10% x 100.000 /1.3 = $7.700

But becuase this is such a High % of your Bankroll you need to readjust teh Bet contiunuasly.

ie if you lose the firts bet then you have a $90k bankroll and the Bet level becomes $6.900.

Of course it is imposssible to do this calculations on the fly.

Aslo in BJ you might lose more than 1 bet (split, doubles etc).

And you also have the issue of Bankroll in hand right now (as opposed to total bankroll)

So you adjust downwards to more prudent levels.

If the AP has $100k bankroll then I think the $2.5k is a good prudent level to play it taking all this considerations into account.

You still get piised of to blow 25% of your bankroll in 10 minutes but shit happens.