0:00:00.000,0:00:05.000 In fact, in English--and in fact, in Greek--there is a particular form of word play 0:00:05.000,0:00:10.000 called syllepsis, based on exploiting this semantic incongruity. 0:00:10.000,0:00:13.000 Let me give you an example of what it looks like in natural language, 0:00:13.000,0:00:15.000 and then we'll bring it back to HTML. 0:00:15.000,0:00:20.000 In this fragment: "she made no reply, up her mind, and a dash for the door" 0:00:20.000,0:00:24.000 "made" is being applied to three different things--replies, 0:00:24.000,0:00:28.000 make up a mind, and make a dash for some location. 0:00:28.000,0:00:30.000 And it means something slightly different in each of these. 0:00:30.000,0:00:32.000 Making a reply means to speak. 0:00:32.000,0:00:35.000 Making up your mind means to decide something. 0:00:35.000,0:00:38.000 And making a dash for the door means to run for the exit. 0:00:38.000,0:00:42.000 But because we have this one function, if you'll permit me, 0:00:42.000,0:00:45.000 being applied to these three different types of arguments, 0:00:45.000,0:00:49.000 there's an incongruity which some may find humorous. 0:00:49.000,0:00:51.000 Here's perhaps my favorite example from the same source. 0:00:51.000,0:00:55.000 "She lowered her standards by raising her glass, her courage, 0:00:55.000,0:00:57.000 her eyes, and his hopes." 0:00:57.000,0:01:00.000 This is a very good but very disconcerting poem 0:01:00.000,0:01:03.000 and a lovely example of syllepsis. 0:01:03.000,0:01:05.000 Lowered is being applied to standards; 0:01:05.000,0:01:09.000 that means to give up your ideals or try something worse. 0:01:09.000,0:01:11.000 Raising her glass, as if in a toast. 0:01:11.000,0:01:15.000 Raising her courage--to muster up her willpower. 0:01:15.000,0:01:17.000 Raising her eyes to look up at someone. 0:01:17.000,0:01:21.000 And raising his hopes because, well, nothing good happens in this poem. 0:01:21.000,0:01:27.000 Similarly, there's an error in HTML known as mismatched tags. 0:01:27.000,0:01:31.000 We talked about balanced parentheses in parsing-- 0:01:31.000,0:01:34.000 the same number of As followed by the same number of Bs, 0:01:34.000,0:01:36.000 or the same number of open parentheses followed by 0:01:36.000,0:01:38.000 the same number of closed parentheses. 0:01:38.000,0:01:41.000 Recall that that's not something we can do with regular languages 0:01:41.000,0:01:45.000 or regular expressions, but we can capture it with a context-free grammar. 0:01:45.000,0:01:48.000 However, we didn't handle it in our parser, 0:01:48.000,0:01:49.000 so we must handle it now. 0:01:49.000,0:01:52.000 This concept is not particularly tricky, 0:01:52.000,0:01:54.000 but it does require a context-free grammar. 0:01:54.000,0:01:57.000 So just to make sure that we're all on the same page, 0:01:57.000,0:01:59.000 there's a bit of a quiz. 0:01:59.000,0:02:01.000 I have written three HTML fragments, 0:02:01.000,0:02:03.000 but I've left some things blank. 0:02:03.000,0:02:07.000 What I would like you to do is fill in each blank with the word 0:02:07.000,0:02:12.000 necessary for each fragment alone to be well-balanced HTML, 0:02:12.000,9:59:59.000 to have its tags match up perfectly.