Grouping/Linear Combination Setup Practice Drill #4

[Dave Killoran]

Hi Leslie,

It's not a problem to draw it that way, although you are repeating the sufficient condition so it's a bit less efficient and I have a concern over possible errors down the line.

So first, when the sufficient condition is F Saturday, if that then happens then yes, F is on Saturday To me it's redundant to say that, but it's not functionally incorrect

Second, my bigger worry is that when taking contrapositive, you might forget that it's a repeat of the sufficient condition, and end up creating a negated term that is broader than what you need. In other words, it's like a trap waiting to happen there. You've drawn it correctly below, but during practice it's easy. under pressure, I wouldn't want you to suddenly start adding conditions.

Also, I will have this appended to the end of viewtopic.php?f=1350&t=6491&start=10, just to keep things all in one place on the Forum.

Thanks!

[leslie7]

Thanks Dave! NP for you appending at all I understand!

Would you be able to tell me if this is possible

"/Hsaw->/Fsae

Just wondering if under this conditional if it is possible for H to live in Saturday West if F is not on Saturday at all?"

[Adam Tyson]

If F is on Saturday, H must also be on Saturday, and H can never be on the East stage. F on Saturday forces H to Saturday-West, which means F could only be Saturday-East. Thus, there is a global inference here that F is never Saturday-West! So I think a better, clearer contrapositive here is to ignore the East/West aspect and just write:

HS FS

(If H is not on Saturday, F is not on Saturday)