Retrospective - API Release To Prevent Minimum Bet Abuse - 19th June

[Sansa]

You can place Lay £0.10 @ 1.16 via the API, but you cannot do it via the website. Obviously the process is different i.e. API uses size reduction, the web uses size increase. I don't know if that was the case yesterday.

[TOM2908]

yes this is absolute rubbish, betfair just round up or down!!!!!!!!!

[Hefi]

If they have problems with the servers why don't they let the applications directly bet under the minimum stake with the precision of two digits (so the real minimum stake would be 0.01). Placing a bet under the minimum bet is 3 operations which is definitely more "spam" than with only one operation.

[geoffw123]

This is getting confusing now isnt it ?
I think we can all agree, it would have been better if Betfair had solved this issue in a different way. (Or post more frequently on this thread at least)

WTPooh, have you tested with the ReplaceOrders command? Moving a lay order of £0.01 up from lower odds to 1.8 is quite happily accepted That is a 25% inflation after rounding from 0.008 to 0.01.

Interesting comment I have just read on this issue from the BetAngel forum. (Some BA users commented that their patched version seems slow, which obviously doesnt make sense with the limited nature of this rounding fix)

We know that this emergency fix had to be done at betfair as they were worried about the stability of the whole exchange if they didn't intervene, so perhaps they've adjusted other internal settings to ease the strain on their servers.

[oldBloke]

There is no inconsistency here.

Lots of inconsistency.

try placing a lay of £0.02 at 1.4 - works

then try placing a back of £0.02 @ 1.4 - rejected

[WTPooh]

Aha thanks for correcting me on this, I just removed my fixes and tested it again with £0.10 @ 1.16. You are correct, it is a 25.00% error and it is rejected. I had naively assumed Betfair would have been consistent on how 25.00% behaves across the tick range.

Betfair if you are reading this, you have a nasty inconsistency in your implementation. Please correct this, or explain to us why it is correct as is. Thanks

P.S Yes Sansa, I was thinking same thing, I guess they have got a small rounding error bug, that they missed in their haste to get this patch out.
Was it a Superman film, where richard pryor made millions exploiting some banks cent rounding loophole ? I think some naughty Betfair user must have been watching that film recently

There is no inconsistency here. 25% and above is always rejected.
When you lay 0.01 @ 1.8 you are getting 20% lower then expected. Everything above 20% is rejected.

[geoffw123]

Aha thanks for correcting me on this, I just removed my fixes and tested it again with £0.10 @ 1.16. You are correct, it is a 25.00% error and it is rejected. I had naively assumed Betfair would have been consistent on how 25.00% behaves across the tick range.

Betfair if you are reading this, you have a nasty inconsistency in your implementation. Please correct this, or explain to us why it is correct as is. Thanks

P.S Yes Sansa, I was thinking same thing, I guess they have got a small rounding error bug, that they missed in their haste to get this patch out.
Was it a Superman film, where richard pryor made millions exploiting some banks cent rounding loophole ? I think some naughty Betfair user must have been watching that film recently

[Sansa]

Assuming that an exact 25% is supposed to be valid. Then for £0.10 @ 1.16 maybe their calculation ends up getting 0.015999 due to some rounding down, instead of 0.016.

I wonder what tomorrow's planned maintenance outage is for?

[oldBloke]

I think they just worded their update a little loosely, as you said lay £0.01 @ 1.8 is right on the change over point, they seem to let an exact 25.00% through as valid. Up a tick would be OK too, but down a tick would fail

This is not always the case ( at the moment )

£0.10 @ 1.16 is also right on the change over point, but it gets rejected.

Hoping betfair will correct or clarify this soon

[bfexplorer]

The current version does not leave a stranded bet. Anyway, I think the purpose of this topic is to hear about the new Betfair rules relating to rounding abuse, not to start comparing software products. With best wishes.

I mentioned that because you have got bug in software leaving your clients to make unnecessary bigger loss on trading bets, that is really bad.The same bug had Bet Angel, other vendors forums did not report such problems.

Can it be done better?

Well of course, if not developers of trading app make unit tests for each critical code, then at least betfair during certification process could discover such problems in software.

That is my point in the previous reply. To the rest, we all need to use api according to betfair T&C.

[Cymatic]

Because when during this "small bet placement" operation if anything goes wrong you need to cancel original minimal + small bet stake, and not leaving it on market as your software and bet angel does. Because then of course user could take actually bigger loss than with it original bet opening trading session.

The current version does not leave a stranded bet. Anyway, I think the purpose of this topic is to hear about the new Betfair rules relating to rounding abuse, not to start comparing software products. With best wishes.

[geoffw123]

As you say, you cannot now blindly place the dummy £2 bet at odds of 1.01, as that can fail when you try the subsequent cancel operation.
I couldnt see a very trivial fix for this so I had to add a calcMinOddsToPlaceDummyLayBet(double layStake) function
Then starting at odds of 1.01 iterate around calculating the true profit and the rounded profit and the percent difference between them, if it fails move up to the next tick and try again, return the lowest odds that passes the new -20/+25 % criteria.
Use the returned odds to place the intial £2 bet at.

Of course that doesnt allow for the scenario where it might return odds of 1.50 say, and the price is already down to 1.05.
You will have to ask Betfair how to workaround that one. They would likely just say tough, you cant.

Regards

[Hefi]

Had someone already implemented a workaround-algorithm for this issue? It is one thing to find the nearest good size/stake combination of the target bet, but we also have to move the initial bet (from above the minimum stake) to our target bet (by checking that we don't place/cancel the order to an 'unfair' bet).

[bfexplorer]

Been running for 12 years then an urgent fix to a "problem" that has always been there.

Can we get access to the "Cash out" API?

Cash out web api must work on the same rules, as it uses the same api internally as rest api is built on.

[LetsGo]

Been running for 12 years then an urgent fix to a "problem" that has always been there.

Can we get access to the "Cash out" API?