The problem with the wrote, wrote, wrote, de, de, de bag of words above is that they don't form a grammatical sentence.

This sentence is grammatically correct.

The sentence is not grammatically accurate.

Strictly speaking, this sentence is grammatically incorrect.

You should try to produce grammatical sentences.

If the value is 1, we replace seconds with second so it's grammatically correct, and then we return that string.

It's grammatically correct, but a native would never say that.

It's grammatically correct, but a native would never say it like that.

The second time, it was the thing we were choosing to expand.

For all three of these cases and regular expressions there is something corresponding we can do in the world of context free grammars.

Units 3 and 4 were relatively abstract to some degree, intentionally so.

In India it was just impossible to paste.

The sentence is free from grammatical mistakes.

Here I have written six possible JavaScript statements.

Finite State Machines, adding a lexer that follows them automatically,

I've written a new grammar over here on the left, but actually if you think about it, it's simpler than our old grammars.

Your English is grammatically correct, but sometimes what you say just doesn't sound like what a native speaker would say.

Strictly speaking, this sentence is not grammatical.

Now we have our formal grammar for JavaScript, and previously we had a formal grammar for HTML, but there's a slight difference between the creative work of making up the grammar, thinking of the right one, designing your own language, making the new Esperanto, and checking utterances to see if they're valid.

A sentence can state something false while at the same time be grammatically correct.

We started off by introducing the concept of a language as a set of strings.

What document is it, precisely, you're talking about?

This is what we're thinking about when we've seen two tokens by not the third.

The set of languages that can be described by re write rules or grammers like this are called context free languages.

You can have a grammar rule that expands to itself, allowing you to have an infinite number of utterances from a finite formal grammar.

A context free grammar can capture the language a N and b N, where N is the same.

I'm sure its grammar is really hard to follow.

These grammars that we've been introducing describe something new context free languages.

You could also come up with examples where G1 and G2 are different, but they're the same exact string, so you could do baa .

In fact, he was born around 1685 and is known for his fugues.

So maybe we'll cancel some debt and all of that.

In theory, you could compose it over here as well.

That is part of what's implemented, and when people implement interpreters or compilers, they usually do it by starting by writing a grammar.

It turns out, yes, although I've been avoiding using the words in class, our memoization approach to parsing really is an instance of dynamic programming.

This is only a partial grammar because it only handles expressions, and it only handles some of the expressions.

To let Parley know the grammatical meaning of a word type.

We humans have always shared with one another.

Her composition had no grammatical errors at all.

Those acronyms are all subsets of context free languages or context free grammars.

We've seen that before with expression goes to expression plus expression.

There are lots of other uses of grammars besides just breaking down programming languages into pieces.

Next question is where do these trees come from?

It's going to turn out that balanced parentheses are one of the first things we've seen that are too complicated to be captured accurately by our old, dearest friend, the regular expressions.

Andrew flips them around and inserts them back in the body

Now it's time once again for you to show your understanding of this forwards and backwards.