I was distracted during this lesson because I am trying to figure out when you would need to use a negation like this?

Example of a bi-conditional:

If it rains it pours

Rains->pours

It pours only if it rains

pours->rains

It pours if and only if it rains

Pours<->rains

It pouring is necessary and sufficient for it raining, it raining is necessary and sufficient for it pouring, they are mutually exclusive. If one happens then the other one happens, if one does not happen the other does not happen!

This is how I would apply this technique.

Obama is is meeting with the first 100 Chicagoans who bought tickets to his new museum. To be in the first 100, you have to get in line before 8:00 am and bought your ticket.

Domain: If a person is a Chicagoan, and if you have bought a ticket, I expect these conditions to already be satisfied.

Rule: If you are in line before 8:00 am, then you will meet Obama.

Disjunction in the necessary condition:

If you like icecream, then you are a kid or you have a sweet tooth.

IC-> K or ST: one of the ideas in the necessary must be true. Both could be true but is not required.

Disjunction in the sufficient condition:

Don't make any noise or go out at night, the creatures will get you.

/N or /GO->Creatures: If you make noise the creatures will get you. Independently, if you go out at night the creatures will get you.

Even if I go to the library everyday, I still have to study.

I go to the library everyday and I have to study.

I go to the library everyday but I have to make sure to study.

-All phrases have the same logical meaning, replacing "but" or "even if"/"even though" for "and" sacrifices some context and nuance but provides the simplicity needed to have the logical foundation.

Conjunction in the sufficient:

If Annie gets adopted and Mel gets adopted then Mrs. Hannigan will have no one to clean the orphanage.

A & M ->CO

Conjunction in the necessary:

If Mrs. Hannigan allows then the girls will have a dog and go to the movies.

H->D & M OR H->D, H->M

@MarcosGuzman415 Those threw me through a loop! It was good practice to see when to use discretion regarding indicator words because my first instinct was to treat line 2 in question 3 like an if/then statement. He says in the lesson that we'll have to think about if the indicator words are denoting something necessary/sufficient. I will definitely need more practice though!

People that have good skincare do not use fragranced products. Alexis' skincare is great, so she must not use neutrogena.

Assumption: Neutrogena is a fragranced skin care product.

All cast members on SNL either had to audition or donated to the show. Michael Kelly did not donate, so he had to have auditioned.

Not all pens are suitable to write on thin paper. For instance, the Pilot G-2 10 bleeds through if the papers isn't at least legal pad paper.

Day one I'm locked in!!!!!