## Logic Games: how do you work out all the combinations?

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Peg

Posts: 331
Joined: Tue Jul 14, 2009 4:32 am

### Logic Games: how do you work out all the combinations?

I've come across a really time consuming type of LG question and can't work out how to do it fast. Example: "How many different total configurations are possible of painters, canvases and paints?"

There are 4 in each variable set, but you also have to work in the rules and limits, so how the hell do you figure out the total number of possible combinations in like 1 minute? The question threw me so much that I actually tried writing out every single hypothetical, and then realized that I was being ridiculous.

I know the previous work is useful here, but it didn't speed me up much. Is there any shortcut you can use that helps you juggle all the variables, and their rules, and come up with the total number of combinations?

gambelda

Posts: 299
Joined: Tue Sep 28, 2010 11:44 am

### Re: Logic Games: how do you work out all the combinations?

I suck at reading comp, but surprisingly games is beyond my strong suit. Sometimes, it is best to do hypootheticals (even with 4 variables). You have to make sure that the rules ACTUALLY LIMIT the options.

This is a common scenario: For example, let's say there are 6 variables (ABCDEF)
A must be either 4th or 6th
C must be either 2nd or 3rd

In this scenario, I often use these two rules as the limitations to the game. They create only 4.
_ C_ A _ _
_C _ _ _ A
_ _ C A _ _
_ _ C _ _ A

Now you have 4 scenarios and you should combine these with other rules. Perhaps one rule says D must be immedietly before E. can you fill this rule into your scenarios? With this rule, you can fill DE immedietly after the A in the first scenario because you know that there is only one placement for it.

Does this help? You should be thinking about what rules are
A) the most limiting - in this scenario, 2 rules combine to limit only 4 possible scenarios
B) what rules then affect the limited scenarios most.

gambelda

Posts: 299
Joined: Tue Sep 28, 2010 11:44 am

### Re: Logic Games: how do you work out all the combinations?

Also in the game you specifically mention, I cant remember what preptest it is from, but I think I have done it.... are you stacking the variable sets and noticing their relations to each other? Often a rule will span across 2 lines of variable sets in these types of questions and SEVERLY limits the options.

almostfamous

Posts: 250
Joined: Sun Jun 20, 2010 2:08 pm

### Re: Logic Games: how do you work out all the combinations?

Usually when a game asks for all possible combinations, it implies that there aren't that many, so there must be some limit in the rules that keeps it down to a reasonable number. If you think there must be 20 different combinations, you're probably missing some key inference.

Peg

Posts: 331
Joined: Tue Jul 14, 2009 4:32 am

### Re: Logic Games: how do you work out all the combinations?

gambelda wrote:Also in the game you specifically mention, I cant remember what preptest it is from, but I think I have done it.... are you stacking the variable sets and noticing their relations to each other? Often a rule will span across 2 lines of variable sets in these types of questions and SEVERLY limits the options.

Thanks for explaining how you broke down the combinations by rule, that actually really helped to do it slightly more quickly. And yes, I stacked the sets vertically; I kind of get what you're saying now about one rule limiting both sets, but you need a lot of space to work this out and I waste a lot of time by erasing previous scribbles to make room for more scribbles, and that takes up seconds too. Is it normal to take longer than one minute on this question type?

Usually when a game asks for all possible combinations, it implies that there aren't that many, so there must be some limit in the rules that keeps it down to a reasonable number. If you think there must be 20 different combinations, you're probably missing some key inference.

I did forget some minimum/maximum limits initially, but by the time I got to this question (it's the final question in the game) I had most of it, but I hadn't written the deductions down to save space for diagrams. I think that might have contributed to the confusion.

gambelda

Posts: 299
Joined: Tue Sep 28, 2010 11:44 am

### Re: Logic Games: how do you work out all the combinations?

Peg wrote:
gambelda wrote:Also in the game you specifically mention, I cant remember what preptest it is from, but I think I have done it.... are you stacking the variable sets and noticing their relations to each other? Often a rule will span across 2 lines of variable sets in these types of questions and SEVERLY limits the options.

Thanks for explaining how you broke down the combinations by rule, that actually really helped to do it slightly more quickly. And yes, I stacked the sets vertically; I kind of get what you're saying now about one rule limiting both sets, but you need a lot of space to work this out and I waste a lot of time by erasing previous scribbles to make room for more scribbles, and that takes up seconds too. Is it normal to take longer than one minute on this question type?

Usually when a game asks for all possible combinations, it implies that there aren't that many, so there must be some limit in the rules that keeps it down to a reasonable number. If you think there must be 20 different combinations, you're probably missing some key inference.

I did forget some minimum/maximum limits initially, but by the time I got to this question (it's the final question in the game) I had most of it, but I hadn't written the deductions down to save space for diagrams. I think that might have contributed to the confusion.

From what I remember, usually games that stack 3 variables, only ever need 1 set up. Are you full utilizing double and triple option rules? I mean if in one space the answer could be A B or C, are you diagramming three different scenarios or just 1 scenario and filling the space with A/B/C?

skip james

Posts: 262
Joined: Sat Sep 19, 2009 2:53 am

### Re: Logic Games: how do you work out all the combinations?

Pretty much never.

I personally believe that the ability to calculate vast numbers of permutations of strings of letters is an over-estimated part of the games section.

I think the games section is (1) pretty goddamn visual (at least in terms of setting up properly (2) hugely conceptual (as in knowing the, usually, very very simple ideas underlying any particular game - these generally repeat) (3) and somewhat analytic from a distanced point of view (like thinking shit like 'hey they haven't given me too much here to work with, perhaps I'm not going have much in my setup and the questions will tend to be local, since they haven't really given me much to answer any must be trues or anything).

Isolating and understanding the key spots that are solvable (i.e. the restricted slots, the variables which force other variables, etc) is much more important to succeeding in games than being a human calculator in my opinion.