How to translate: "Jack must wear every colour Fred wears"

cnavarro495

Hi guys,

This is such a stupid question but as the title says, how do you translate: "Jack must wear every colour Fred wears" into Lawgic

Is it F-->J ?

My confusion stems from the fact that there are 2 lawgic indicators (must and every) here. I actually missed "every" initially and thought it was only must so I diagrammed it as J-->F.

Should I interpret it as: "Every colour Fred wears must be worn by Jack" ?

Sorry for the silly question haha just want to be sure.

Rigid Designator

Yes you're right.

If Jack must wear every colour that Fred wears it follows that if Fred wears a given colour then Jack wears that colour.

dml277

Another way to look at this is that "must" is applied to Jack while "every" is applied to Fred. Who must do something if something happens? Jack. Every color someone wears? Who? Fred.

tams2018

what is guaranteed from that statement? Jack wears that color.

If Fred wears it, Jack wears it.

F --> J

It would be helpful to read the statement and figure out what is guaranteed rather than looking for indicators.

TheMikey

yup! F-->J

if it were J-->F then it would read the reverse of the statement "Jack must wear every colour Fred wears" to "Fred must wear every colour Jack wears"

ProgressNotPerfection

The way you have it diagrammed is right (F-->J). Keep in mind though that since Jack is the on the necessary side, that he can wear a colour other than what Fred is wearing. Fred wearing a particular colour is SUFFICIENT for it to be NECESSARY that Jack wears that colour, but Jack is not limited to only those colours. The rule doesn't apply any necessary conditions to Jack wearing a colour, only to Fred.

Think of it this way, "if Fred is wearing a colour, then Jack must wear it too". What this doesn't say is that Jack can ONLY wear the colours that Fred is wearing, or "Jack will wear a colour if, and only if, it is worn by Fred". If that were the case it would be a double arrow indicating that they will wear the same colours (F<----->J). But since the arrow only goes one way, Fred and Jack do not have to wear the same colours.

I hope this wasn't too confusing!!