4.4 If-then Identifiers

IF can be replaced with…

EACH, EVERY, ANY, and ALL; They refer to the trigger

Qs for all Rs

Qs IF Rs; R → Q

All Rs are Qs

IF Rs then Qs; R → Q

ONLY and ONLY IF should be replaced with…

An arrow; They refer to the result

R only if Q

R→Q

Only if Q, R

→Q, R: R→Q

Unless translates to…

“IF NOT…”; it is a negative term

R unless Q

R IF NOT Q; ~Q→R

Unless Q, R

IF NOT Q, R; ~Q→R

“IF AND ONLY IF” means…

The relationship between the elements goes both ways; D→W→D or W→D→W

All people who attend Jeff’s party will attend Kathryn’s party

J→K

Brennan will attend every session that Kendall will attend

K→B

Johnny will drink beer only if Sally will also.

J→S

Only students who attend the boat party will attend the dance.

D→B

Lauren must prepare lunch unless Amy does.

~A→L

Unless Stuart goes fishing, Parker must go fishing

~S→P

If you are in prison, then you must give your cigarettes to Guido any time that he asks for them.

Prison→Asks→Give

If you branch the trigger and the result…

I is an if and only if; S→B→S

How do you negate this if-then statement: If one is a UT student, then one is drunk.

At least one UT student is not a drunk.