Okay.

So can you hear me properly?

Okay.

So yeah, then we'll just redo this quiz next

week as well.

Gives you some extra time to study logic, which anyway most of you need.

So last week we started with logic, specifically propositional logic.

The way Kohl has it does

besides it may seem a bit overwhelming at first.

That's because he is doing the general

approach how to teach logic using propositional logic as the example.

Propositional logic

is the simplest logic we have.

And we're going to learn a couple more complicated ones afterwards.

So as I said, I'm the one who always sets the exams and oversees the grading.

The logic

problems are often the ones that students struggle the most with.

Right after the prologue

problem, which many students don't even attempt for reasons I don't understand.

So it seems

that a lot of students really just don't understand how logic works at all and just randomly guess

the answers, which of course never works.

So I've been told that you guys ask a lot

more questions than the previous batches.

So that's good.

So I strongly encourage you

to ask a lot of questions about logic.

Go to the tutorials, ask in the lecture, have

study groups.

It isn't actually that much to learn.

It's all about getting your brain

to think a bit differently and to understand the way logic works.

So with logic, there's

always three different components.

The first one is what we call the syntax.

And the syntax

just describes the stuff we can write down.

So you can think of an analogy to a programming

language.

The syntax is what you need just to parse and maybe type check your program.

So ultimately, we have a grammar.

Already the first complication is it's not just one

grammar, it's really a family of grammars.

Because we have to say what kind of propositional

variables we have.

So we usually call it the signature.

Now, due to programming languages,

again, it's kind of the header file.

It tells you all the names that are available that

in addition to the built in ones.