# How is the PS open raising chart derived?

• Gold
Joined: 03.12.2011
I wasn't quite able to figure out the exact principle according to which the PS open raising chart for FL has been derived. I then decided to put the question here. Maybe this has already been explained somewhere, in that case please point me to that explanation.

I figured so much that the ORC must be based on some kind of approximation, since completely simulating e.g. a six-handed FL game would be totally intractable.

However I could only speculate whether the ORC takes into account any post-flop gameplay (in form of either heuristics or via some simple simulation model) or whether it's solely based on pre-flop equities. Or maybe the ORC isn't even completely systematic but is compiled by some expert. As said, I don't know but I'd be very interested in knowing.

One reason I would like to know is that I've played with the thought of doing some simulations myself for fun. It would nice to have a solid baseline for comparison of the results. And the ORC is not that kind of solid baseline unless I manage to figure out how it has been compiled. Maybe it could be a fun exercise to apply the same principles also to some other games.

Simulating is much more stress-free than actually playing - one completely avoids the variance.
• 5 replies
• Bronze
Joined: 15.06.2009
Do you have the Equilab?

That's what you need for simulation, and you might even be able to reverse engineer how the ORC is derived.

Here: http://www.pokerstrategy.com/software/

/Johan =
• Gold
Joined: 03.12.2011
Originally posted by YohanN7
Do you have the Equilab?
Yes.

That's what you need for simulation, and you might even be able to reverse engineer how the ORC is derived.
Nice piece of software and very handy to answer questions it is intended to answer. That is, questions concerning the equities if the hand went all-in pre-flop (or actually any other pre-specified moment) and nobody folded their hands at any stage. However, it is not very easy to interface Equilab with other simulation code that would model the folding and betting actions of other players.

Does anyone know whether the ORC is based on such simplification where you just measure the pre-flop equity of hands against the random hands of remaining opponents? I can see how this sort of chart could be generated with Equilab.

Edit:

I tried, this is not he way things are done. The opening ranges become ridiculously wide if we assume the opponents to call us with every 72 and that we don't lose any additional money against AA.

Does anyone have any experience whether such starting hand ranges would differ significantly with the case of employing a more realistic model of pre-flop play, and maybe even post-flop?
• Bronze
Joined: 15.06.2009
Have you checked the articles? There is at least one article going into pre-flop theory. And, there is one going into Equilab too.

It is probably a gold article, so I can't look myself at the moment.

/Johan =
• Gold
Joined: 03.12.2011
Originally posted by YohanN7
Have you checked the articles? There is at least one article going into pre-flop theory. And, there is one going into Equilab too.
Naturally I've tried to find that information in those strategy articles. With several readings I haven't been successful yet. Maybe it's somewhere there, someone smarter help me out.

The way I understand the articles is that they take the ORC as the starting point and discuss how to proceed pre-flop given that knowledge. And that discussion even I can follow.

Maybe the "secret" behind the derivation of the ORC is really simple, yet I can't figure it out. Wouldn't be the first time such things happen.
• Gold
Joined: 03.12.2011
I read the strategy articles once more. I'm now quite confident that the principle of deriving the ORC is not explicitly mentioned in the articles. I found a statement that says that besides ensuring enough equity against random hands the ORC takes into account that someone after you might raise you with a better hand. Then it states that "the ORC is based on huge databases and incredibly vast experience" (my own translation).

So I guess we're still in the starting point of my original question: is the ORC based on some formal model or does the incorporation of expert knowledge and database analysis involve heuristic criteria ("I'm the expert and I feel like playing this hand from this pos. usually is profitable")? And, in either case, how does one exactly get the chart?