The Foul and a Miss rule is probably the most complicated rule in any game played with round balls and a cue stick on a rectangular table. It is rarely fully understood and often miss-characterized. Even among avid Snooker players, most don't remember all the details. Now I know some of you are going to say, yes I do know the rule well, and you probably do. But unfortunately the rule is not without some subjectivity in application, and trying to really understand its interpretive parts is difficult.
Having to implement this rule in Virtual Pool was very difficult and time-consuming. The interpretive parts caused particular issue, and getting the details right wasn't easy either.
What I can say up front about the design of the rule implementation is:
I am somewhat of an expert on rules after having to read and implement so many rule sets. I did assist in rewriting the BCA rules which for some games became the World Rules.
We did talk to a professional referee in reference to some of questions we had about Foul and a Miss
We also communicated with several Snooker clubs about how they apply Foul and a Miss
So first in review, I'm going to cover the basic parts of Foul and a Miss. Not discussed here are all the little details of when the rule does not apply based on score, balls on the table, etc.. You can read about all those here:
When your opponent completely misses the ball/s on, it is a foul, and in most situations a Foul and a Miss. If it is considered a Foul and a Miss, you have a choice. You can have your opponent play again from where all the balls stop, or make you opponent take the entire shot over. The entire shot over means that all the balls are put back into place. In Virtual Pool we can guarantee the shot is exactly the same, in RL, that is impossible, just best guess.
So given that all the exception cases for Foul and a Miss don't apply for a complete miss, exactly how do we determine if the shot was a Foul and a Miss?
It is a Foul and a Miss for sure: “If the striker, in making a stroke, fails to first hit a ball on when there is a clear path in a straight line from the cue-ball to any part of any ball that is or could be on, the referee shall call FOUL AND A MISS “
So what this is saying is if not a full Snooker, where full means to part of the ball on can be hit, it is always called Foul and a Miss (note except for the points, balls exceptions).
Where things get less clear is when there is a full snooker on the shot. This paragraph pretty much covers everything else:
“The striker shall, to the best of his ability, endeavour to hit the ball on. If the referee considers the Rule infringed, he shall call FOUL AND A MISS unless only the Black remains on the table, or a situation exists where it is impossible to hit the ball on. In the latter case it must be assumed the striker is attempting to hit the ball on provided that he plays, directly or indirectly, at the ball on with sufficient strength, in the referee's opinion, to have reached the ball on but for the obstructing ball or balls. “
The bit about only the Black remaining is one of those exception cases, but essentially this says that unless the ball on is impossible to hit then the referee has to make a ruling.
When they say “impossible”, that means really means impossible, NOT unlikely, very unlikely, or for all practical purposes unlikely. For an example of impossible, imagine the cue ball in the pocket jaws with 3 reds around the pocket, and no gaps large enough for it to fit through. If the ball on is a colour this is an impossible hit. Jump shots are not legal in Snooker and there is no path out to contact a colour.
So how does the referee decide is if is a Foul and a Miss when not impossible? Well the first sentence of the paragraph quoted gives the criteria:
“The striker shall, to the best of his ability, endeavour to hit the ball on.”
So the rule references the players ability or skill level, why? Well to fully appreciate that statement you have to look at why the Foul and a Miss rule was implemented. The purpose is to stop players from missing on purpose to gain advantage in the game. Think about a situation where playing the shot to hit the ball on will most likely result in a large scoring run for your opponent. Missing, taking the point penalty, and even shooting again might be better than trying to hit the ball on. So the Foul and a Miss rule was put in to prevent this.
Many of you get the understanding of Foul and a Miss from watching professional snooker. Professional Snooker is the easiest situation in dealing with the interpretive part of the rule. Since all the players are pros, it is easy to come up with a pretty consistent criteria for if the shot is a Foul and a Miss. For pros they are going to call Foul and a Miss almost always, even for shots requiring 3 or 4 rail kicks, masse shots, etc. These guys are the best so they call it that way, even if the pro really was trying to hit the ball, they are going to call Foul and a Miss.
When less skilled players are playing Snooker, it can't be called the same way as for the pros. Imagine a guy how is lucky to make 2 balls in a row having to hit a multi-rail kick shot where the path must be changed by applying spin to the cue ball. The guy could lose 100 points or more and never hit the ball on.
So we have to adjust the criteria for calling Foul and a Miss based on the skill level of the player. Lucky for us Virtual Pool already has a skill level identifier for Snooker called a rating. The rating is a numerical representation of player skill level. Here is how VP decides foul and miss based on skill level:
> 1900 Possible to hit with a multi-rail kick with cue ball spin, up to 4 rails
> 1700 Possible to hit with a 1 rail kick with cue ball spin
> 1500 Possible to hit with a 1 rail kick no cue ball spin
< 1500 not called unless there is a direct path to the ball (not a full snooker)
This method is not perfect, but it does a reasonable job in most situations of making a fair call. We may tweak the criteria or skill level breaks, as time goes on, to make this a better fit to player skill.
Hope that give all of you a better understanding of Foul and a Miss and the VP referee implementation of the rule.
Virtual Pool 4 Online
February 27, 2014