Strategies for In/Out Selection Games? Forum

[FlyHigh]

Struggling with these. Usually get anywhere from 1 to 3 wrong. Can you guys please share some strategies? Thanks!

[Campagnolo]

Write out each rule and write the contrapositive underneath.

If it's an in/out game, include the out group in your setup. Some say this isn't important, but I think it's vital. If you get a rule like A --> ~B, for example, you can put A/B in the out group because the conditional statement tells you that A or B but not both may be in.

If you're stuck, go back to the rules. Always go back to the rules. They are your friends, and want to help you.

[tmon]

It often helps to link up rules and their contrapositives. Many times it turns out that the rules create one long chain that speeds up the process.
If you've done that and you're still struggling, have a look at Manhattan's LG guide. I believe this is one of the game types where they provide a fairly unique approach that has helped some people.

[bhan87]

For global setups and all hypos, always include an "out" group to fill in. Make sure, if possibly, to make clear how many slots are still available in each group. Many times, you'll find that all the "out" slots are taken, so every other variable must be in or vice versa.

For conditional statements that share the same variables, always connect them together. For example:

A->B
B-> not C
D-> C

Take the contrapositive of the last statement to get "not C -> not D" and combine everything to get A->B->not C->not D

Sometimes a simple chain like that will take up nearly all the slots available in either the in or out group. From that, you can usually infer that a different variable will force too many players in or out. For example, say you have 4 slots for in and 3 slots for out. A question says A must be in, thus

In: A B [] []
Out: C D []

Say for the remaining variables (E F G) we have the following rule:

Not E -> Not F
Contrapositive: F -> E

Look closely. What happens if you put E in the out group? Too many people out because it'll force F out too. That means E has to be in:

In: A B E [F/G]
Out: C D [G/F]

An answer choice may very well be that E must be in. Or, if the question was being difficult it might say F and G must be in different groups. You couldn't have figured that out without the conditional chain and the out group labelled. (Special note, F doesn't have to be in, a common mistake)

Alternatively, say the question was being generous and says that F must be in, then according to the contrapositive, E has to follow:

In: A B F E
Out: C D G

Because all the In group slots are full, ANYTHING leftover must be out.

[bp shinners]

Third-ing the inclusion of an 'Out' group.

Also, for In and Out games (or any grouping game, for that matter), check to see if any variable comes up in a number of rules. If you've got 3 rules about H, for example, set up different scenarios. There are only going to be a number of scenarios equal to the number of groups, less if H can't go in a certain group.

So:

1) In an In and Out game, make one scenario where H is In, one scenario where H is out. H's appearance in a number of rules will let you fill in several other slots, and you'll be able to get through the questions quickly.

2) In a multi-group grouping game, make a scenario for H in each group. Again, you can usually fill quite a few things out if you picked the right player (the one with several rules).

Generally, these scenarios take some time up front, but save you a ton of time when you get into the questions.

[ColtsFan88]

For my in/out games I would make an in and out group by simply drawing a horizontal line. ____________

Any items "in" go above the line, any "out" go below the line. I found it easy to keep track of everything this way.

[paul34]

.

[Angrygeopolitically]

No

a,b,c,d,e,f,g,
---------------------------------------
in l out
ifa------- l ------b
l
ifc----d l
l
if d--f,g l
l
if e ------l----g

then jus write the hypos below. No need to write the contra-positives. This should be the easiest type of game.

[Angrygeopolitically]

For my in/out games I would make an in and out group by simply drawing a horizontal line. ____________

Any items "in" go above the line, any "out" go below the line. I found it easy to keep track of everything this way.

I do the same thing but with a vertical line and then I add a line if it is three groups like: group A l group B l group C l