Okay, there we go.

That looks somewhat reasonable, I guess.

We definitely know what everyone can do.

We know what people struggle with, which is pretty much what I expected.

Actually do we have any particular questions maybe?

Yes.

Okay.

Okay, maybe let's get to that at the end of the lecture then.

You had a question?

Yeah.

With respect to the quiz?

Yeah.

Okay.

In the quiz we had given a signature and then we had to say what are the values of

the position using according to the present.

Yep.

I don't know how to approach that.

Okay, I don't know how to approach that by staring at this thing basically.

This gives you a precise prescription of what makes up a proper well-formed formula or a

proper well-formed term, right?

Mostly the tricky thing with respect to the quiz was that I made multiplication a predicate

unary function symbol because I can and because I want you to learn that symbols don't mean

anything basically.

And then you just need to check what it says here, right?

So if you have a unary function symbol, for example, what you're supposed to do is you're

supposed to, where is it?

Here.

What you're supposed to do is you take the symbol, then you follow it by an open parenthesis,

then you follow it by the arguments and then you follow it by a closed parenthesis, right?

So everything that says plus open parenthesis, one single term, closed parenthesis is properly

well-formed if it plus is a unary function symbol.

If it were a binary function symbol as you would usually expect, then of course you would

also expect a comma in there and have a second term somewhere.

And then for like multiplication, well, for some reason I figured I would use that as

a predicate symbol.

You have to look at this particular case, right?

So if multiplication is in sigma, in this case, P2 and T1, T2 in this case are well-formed

terms, then multiplication followed by an open parenthesis followed by two terms separated

by a comma followed by a closed parenthesis is again a formula.

Sure.

Okay so everybody agreed on this one, right?

I don't think anybody needs help with this one.

Ah, sorry.

Yes, I can.

Ah, much better.

Same probably here.

Okay, so, and maybe let's go over them.

The first one is the first one correct formula.

Yes?

Oh, good point.