Because a programme can scrape the necessary information from their web page and submit bets automatically. The betfair server just receives a block of binary code and has no way of knowing whether it was submitted by a manual user and generated by the web page or was submitted by a user programme. The way to combat it is by limiting the information available to bots.

well you're wrong then.

you could only ban on suspected activity.

you could make it very difficult to operate a bot, but ultimately all communciation between your PC and betfair's servers which can be performed via a website, can be sent programatically.

STEPTOES YARD     28 Dec 11 23:55 
amazed more of that 29s didnt go

Actually I'm amazed that so much was taken.

If I'd been playing the race, and seen that lay offered in-running, I would have assumed someone had spotted the horse go the wrong side of a marker or lose its weight cloth and I hadn't. Especially in a race shown on split screen.

Yes, on reflection the price offered didn't really match that scenario, but in the hurly burly of a horse race on a split screen, I would have just let the opportunity go.

For comparison, when Inzamam-Ul-Haq refused to come out after tea in the Oval Test vs England, double figure prices were offered about an England victory for a lot longer than this horse race took to run, yet weren't taken, and that was as big a gift. But, again, only with hindsight.

Are we take it then that the magic 2^31 number is what led to this mess?

Not being a techie, is that sommething important in a tech sense ?

That's an explanation in this context ?

If the bet size was 2^31+1 pence = 21,474,836.50 pounds

a 32 bit signed integer would interpret that as

-1 penny

and presumably that times 28 would be considered below the account available funds.

Fixing this appears to trivial. Once the problem is known.

But we can only speculate as to future impact.

Betfair's full disclosure is garbage.

So if it's not giving us the full or true story, how can any of us say what other risks there may be out there?

The forumite DStyle was the one who first suggested the 32 bit integer theory. Well done to him.

However, I still have some further questions on this issue.

1. 2^31 equals 2 147 483 648. In pounds this is £21,474.364.48. In signed and unsigned bits, this number represents 0 I believe? I.e 21,474.364.47 (1 less than 2^31) is the maximum number Betfair can store in memory. However surely Betfair's software had some kind of fail-safe mechanism if it recieved a negative value (£21,474.364.49 would equal -1)*28= -0.28. How is it possible to have negative exposure? Surely, a negative value should have triggered some kind of error?

2. The punter in question had £1000 in his account. Therefore am I right in saying that if he submitted a bet anywhere between £21,474,364.47 and £21,474,872.19 (which in signed/unsiged bits would represent -3571 or -£35.71 * 28 = £999.88), the same thing would have happened. So the significane of 2^31 isn't so important, once the number was between 2^31 and 2^31+3571 is the crucial thing?

Am I correct?

This is undisclosed and I think it's a poor show to state in a bulletin that they are giving us all the known facts when clearly they are not.

That said, does it really matter?  What this incident proves, if anything, is that even the most tried and tested computer system will still have bugs in.  Anyone who says otherwise is either lying or not au fair with the binary world.

What we can say quite categorically is that Betfair has one of the most advanced, tried, tested and robust databases anywhere on the planet.

What has probably happened is a combination of 2 errors occurring at the same time

1.....a customers bot has multiplied a series of bets that has equaled an overflow figure
in total stake at 32 bit size data.

2.....a fatal flaw was programmed in the part of the api that checks the total amount of stake
of an account that needs matching and has allowed the bet to be matched because of incorrect bit parity testing of overflow numbers.

or to put into laymans terms , a bug existed in the betfair API bet matching bot.

all this goes to prove that if you combine the talents of 2 fools you get a result
far greater than than the total sum of the parts!

bf_fanatic, is the API programmed differently to the normal Betfair system that us mortals use? I would have thought if the API was designed after, most of it's code would be a matter of copy and paste, and then add in the extra functionality afterewards.

what usually happens is that once it gets passed a certain stage, then certain assumptions are made about it otherwise your checking and double checking the same number over and over

Would imagine the first check validation has changed subtly and allowed a number in the it shouldnt of and the rest of software has just assumed it is correct/valid. Some recent upgrade or sumfink

you would never expect any sane punter to place such large total stake value on any event item outcome but you still have to make your code idiot proof

The API would be accepting all sorts of sh!te from everywhere would make me think its some recent code change. Thats usually the reason bug get added. Classic regression

Could still be a unique set of events that have never happened before but that would be really freaky!

The most frightning scenario of automated madness is the amount of nuclear warheads that can be sent to there targets by a series of atomated detection ssytems around the world but thankfully the process is intervened with a phone call to a nation leader whos has the sense to stop and say"this doesnt make sense"

the automated forex software that runs everyday has the power to bring the world to its knees in the event of market freefall, one hopes humans are allowed to intervine these processes also.

machines can be very dangerous indeed.

Slightly off topic but the markets in Europe and the euro are one thing that are massively affected by computer software with pre-programmed commands. Something triggers a drop in the euro's value vs the dollar. Someone's programme is designed to sell once the euro drops below a certain value, this pushes the euro's worth down further, so somebody else sells, and it drops again, and another person sells. Bf_Fananatic you are right. Machines are very dangerous. Could ultimately bring down the euro !!!

the euro experiment is on-going and of grave concern to all, because generally we abide and live in a capitalist enviroment we have to endure what ever the mass distribution of gloabal wealth provides in terms of poverty and richness.

"but then again bookmakers arent brave enough to engage in such activity that betfair take on every second of every day via automation. "

Betfair brave??? I think you'll find it's the punters on here that carry the can every second on here, bf.