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In fact, in English--and in fact, in Greek--there is a particular form of word play

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called syllepsis, based on exploiting this semantic incongruity.

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Let me give you an example of what it looks like in natural language,

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and then we'll bring it back to HTML.

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In this fragment: "she made no reply, up her mind, and a dash for the door"

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"made" is being applied to three different things--replies,

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make up a mind, and make a dash for some location.

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And it means something slightly different in each of these.

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Making a reply means to speak.

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Making up your mind means to decide something.

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And making a dash for the door means to run for the exit.

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But because we have this one function, if you'll permit me,

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being applied to these three different types of arguments,

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there's an incongruity which some may find humorous.

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Here's perhaps my favorite example from the same source.

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"She lowered her standards by raising her glass, her courage,

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her eyes, and his hopes."

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This is a very good but very disconcerting poem

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and a lovely example of syllepsis.

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Lowered is being applied to standards;

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that means to give up your ideals or try something worse.

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Raising her glass, as if in a toast.

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Raising her courage--to muster up her willpower.

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Raising her eyes to look up at someone.

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And raising his hopes because, well, nothing good happens in this poem.

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Similarly, there's an error in HTML known as mismatched tags.

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We talked about balanced parentheses in parsing--

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the same number of As followed by the same number of Bs,

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or the same number of open parentheses followed by

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the same number of closed parentheses.

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Recall that that's not something we can do with regular languages

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or regular expressions, but we can capture it with a context-free grammar.

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However, we didn't handle it in our parser,

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so we must handle it now.

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This concept is not particularly tricky,

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but it does require a context-free grammar.

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So just to make sure that we're all on the same page,

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there's a bit of a quiz.

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I have written three HTML fragments,

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but I've left some things blank.

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What I would like you to do is fill in each blank with the word

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necessary for each fragment alone to be well-balanced HTML,

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to have its tags match up perfectly.