hey everyone welcome to the last video this week okay so in this video we want to talk about ambiguity again so particularly structural ambiguity of sentences and so we have the sentence darth vader will poke the dog with the lightsaber and this has two distinct interpretations right and so the first interpretation is the one in which darth vader is using the lightsaber to poke the dog and the other interpretation is there's a dog who has on the lightsaber and darth vader poked this dog that's the other interpretation okay and so uh now we have the tools to explain what's going on with these two interpretations and so uh in both of those interpretations uh the same words are used okay but the the difference between the two interpretations is what forms a constituent in each one okay so let's take a look at the structure of each of these interpretations let's take a look at the first interpretation which is darth vader is using a lightsaber to poke the dog and so in this case right in both of these interpretations the culprit is with the lightsaber that prepositional phrase depending on what this prepositional phrase is modifying it creates different interpretations so first of all let's label the categories there's a couple of things i want to note in this one um and so darth vader is a name uh and so i'm just gonna smash darth vader together as one thing so proper nouns and common nouns actually have a lot of the same behavior and so even something like darth vader can be appreciated by determiners in some context so if there were multiple darth vaders um for example like you know darth vader in this movie versus like the darth vader in that one uh the other movie uh you could say something like this darth vader versus that darth vader um and so it's definitely able to be appreciated by a determiner in some context so it's definitely a noun you could have multiple darth vaders you know things like that and so uh yeah it's definitely a noun i'm gonna skip will for a second and so poke the dog with the lightsaber i think the rest of it is not so bad okay so we haven't seen a sentence with an auxiliary yet and so um will is not the main verb of the sentence but the auxiliary verb and so you know because when you ask a question um the will is going to move to the front so will darth vader poke the dog with the lightsaber and so we're simply going to call this um will auxiliary uh in this class make sure you don't label it as a verb so the v for verve means main verb and so the auxiliary verb should be distinguished from that okay so there are some things that we know um and so in terms of the constituency for example we know that the lightsaber forms an it constituent right and so darth vader will poke the dog with it i mean so we definitely know that this is a constituent right here the other thing that we know is that with the lightsaber is also a constituent okay um and so in this case right with the lightsaber is not an answer to when and it's also not an answer to where and so in this case the then and their substitution test is not gonna work because on substituting with the lightsaber if then or there is going to change the meaning of the original sentence if you say darth vader will poke the dog then right that's not what the original sentence means okay but there are some other indications that with the lightsaber is a constituent particularly for this interpretation for example which has to do with the fact that you know it forms a unit of sense right with what with the lightsaber the lightsaber is the object of width giving it more information about with you know what right so for this particular interpretation you can say something like it is with the lightsaber that darth vader will poke the dog right and so what you can tell here is that with the lightsaber it can also be displaced to the front and so suggesting that this is a very much a constituent okay but you probably already have a good intuition with the lightsaber sounds like a prepositional phrase anyway and so let's go ahead with that okay so whenever you have an ambiguous sentence if you have for example two different interpretations of the sentence that means that two different structures should be possible for that given sentence okay so first of all figure out what's causing the ambiguity so in this case the culprit is with the lightsaber that's what's causing the ambiguity really because um several things can be modified by this prepositional phrase in this sentence so let's think about this particular interpretation okay so what's happening with the lightsaber in this interpretation it's the poking that's happening right and so it's something about the poking process with the lightsaber okay so if you think that's the case then what you need to do is form a do so constituent such that it'll produce the interpretation that you're looking for so the cool thing about substitution is that sometimes a particular substitution will produce obligatory one of the interpretations so sometimes it gets rid of the ambiguity when you do the substitution test and when you do that kind of substitution test and you only get one interpretation then that's how you know that that's the group of words that are supposed to go together for that particular interpretation okay so we know with the lightsaber or something about poking but you know the word poke is not next to the prepositional phrase with the lightsaber it's not just poke that's happening right but you know it's something about poke so what you're looking for is some sort of verb phrase constituent right here some sort of do so constituent okay so one thing that we know is that what's being poked is the dog okay so importantly the dog doesn't have the lightsaber in this interpretation so you want to be careful about you know leaving the prepositional phrase alone still you don't want to combine the prepositional phrase with dog or anything like that okay so in this case we're going to try the do so constituent test okay what happens if you replace poke the dog with do so okay darth vader will poke the dog with the lightsaber darth vader will do so with the lightsaber okay so something interesting has happened when you replace poke the dog with do so okay you only get one interpretation when you say he will do so with a lightsaber you only get the interpretation in this picture where he is doing the poking using the lightsaber that's exactly the interpretation that we want so that means you've found the right constituent for this particular interpretation does that make sense right so try the uh if you think the prepositional phrase is modifying the the verb thing right the the verb unit right there uh and so if that's the case uh try the do so substitution test to confirm that those things are supposed to go together and if you are successful you should get the correct interpretation as a result of the substitution okay so let's build up this do so constituent because there's more stuff in with within and so if you say darth vader or a poke it with the lightsaber so it can replace the dog okay and so you have the dog right here and then of course poke the dog right okay all right so that's the do so constituent and importantly in this particular interpretation this prepositional phrase is forming a unit of sense with poke the dog right because it's giving you more information about how the poking of the dog was done okay it is with this instrument that the poking took place okay so that forms a unit of sense together with poke the dog okay to show that you can do another do so substitution test so if you put this entire thing together you get something like darth vader or poke the dog with the lightsaber darth vader will do so okay so that entire thing can be replaced with do so without changing the meaning of the sentence so you get this constituent right here okay the next question is this issue a will okay and so what do we do with will okay um is you have two options you can connect the will to the verb phrase that you just created or the will can connect to darth vader um and so which one do you think is correct which where should the auxiliary go okay so in thinking about this uh you want to think about like what we learned about you know these categories and so so which category are auxiliaries closely tied to okay so you have two options right here you have a nouny thing that it can attach to or a verbi thing that it can attach to okay which one do you think will should go with yeah i think the answer here is it should go with the verb phrase right because will forms um a unit of sense of poke the dog with the lightsaber it tells you the tense right like when this event took place really is what this tells you so the auxiliary always goes with the verb phrase the biggest verb phrase that you create in the end like this okay so finish creating your big verb phrase and then once you have the subject the auxiliary and the verb phrase i'll connect the auxiliary to the verb phrase and then the subject connects to that at the end like so got it so this is the tree for darth vader will poke the dog with the lightsaber for this particular interpretation this is where darth vader is using the lightsaber in order to poke the dog okay how about the other interpretation okay so in this interpretation it is the dog who has the lightsaber and darth vader is simply poking him with his finger okay okay so darth vader will poke the dog with the lightsaber okay so the same thing happened so let's do the categories first so we already know that with the lightsaber is a prepositional phrase and in this particular interpretation it needs to connect to something else so that we can produce the right interpretation for this particular context okay the key here is is that the dog has the lightsaber so with the lightsaber is telling you something about dog and so you should form a unit of sense with dog and so modifier of dog right here okay so that means that we're looking for a nouny constituent right and so what we should be trying is a one substitution test so let's try this so with the lightsaber is naturally about the dog in this interpretation so put that together and see what happens okay darth vader will poke the dog with the lightsaber okay so let's replace dog with the lightsaber with one okay so let's try this instead of the okay okay this will sound like darth vader will poke this one darth vader or poke the dog the lightsaber darth vader or poke this one okay okay so the again the interesting thing is you found the right constituent right here because when you say darth vader will poke this one okay that only has the interpretation that you're talking about a dog who has the lightsaber okay so imagine that there are multiple dogs with the lightsaber okay and you're asking which one is he going to poke and then you can answer that with darth vader poke this one right and when you say it like that this one right the only available interpretation is that it's the dog who has the lightsaber and there's no other available interpretation so this one substitution is the crucial substitution right here so let's put that together okay so we have something like this and then the rest of it is pretty much you know the same as usual and so the dog with the lightsaber and so the other constituent that's important is this it right and so darth vader will poke it okay that also clearly gives you one of the interpretations the relevant one right here okay and then what are we poking we're poking the dog with the lightsaber right so you can see right here that the dog with the lightsaber is one unit right here that's being poked so let's try this substitution uh darth vader will poke the dog to the lightsaber darth vader will do so okay so the entire end is replace of do so and that sounds good to me okay and then of course the auxiliary verb goes with the biggest verb phrase that you created and then the subject gets connected to that to form the sentence as a constituent okay makes sense okay so here's one thing that i want to show you um there is a very common mistake that people make with something like this okay so sometimes you see this interpretation oh it's the dog who has a lightsaber and so sometimes students have the impulse to be like okay oh i should put the dog together as a constituent like this because determiners and nouns go together and then they connect the prepositional phrase to that okay but you want to be really careful about this because if you say that the dog is a constituent right here you really have to try the pronoun substitution to make sure that the the interpretation that it creates is the correct interpretation let's see what happens and so the dog if put together should be it okay so let's read the sentence with the dog replaced as it okay darth vader will poke it with the lightsaber darth vader will poke it with the lightsaber darth vader repoket with the lightsaber okay so the funny thing is if you replace the dog with it it gives you the other interpretation right it sounds like you're using the lightsaber to poke the dog and you don't get the interpretation that it's the dog who has the lightsaber so this kind of structure is incorrect okay um and so once again now whenever you have a prepositional phrase modifying a noun thing it really is directly modifying the noun instead of that determiner noun unit right here okay so it never modifies like that sort of pronominal unit like this okay so how do you know this is wrong well you know if you put the and dog together if you hypothesize that this is a constituent determiner and a noun together then it should replace with a pronoun without changing the meaning of the sentence but if you say darth vader or poke it with the lightsaber you get the wrong interpretation so it's impossible for this to be the correct structure okay so be careful about that um and so whenever you have a prepositional phrase think really hard about what it's it's forming a unit of sense with it's it's either the noun or some sort of verb phrase typically and so make sure you look around for that okay so here's another one and this is going to sound familiar because we introduced this sentence earlier in the semester okay dozens rally for peace and buffalo and so this is a news headline and so we were talking about ambiguity earlier in the semester and we were trying to figure out what the two possible interpretations are okay so you guys told me that there's two possible interpretations so the first one was that you know there was a rally for peace taking place uh and then this thing took place in buffalo so the prepositional phrase is telling you something about the verb phrase right here where the rallying took place the other interpretation was it was a particular kind of piece right and so peace in buffalo is what people rally for with was the other interpretation okay so for this particular headline the intended interpretation was the first one and so the rallying for peace took place in buffalo so let's see what the structure for the intended interpretation looks like so the the the interpretation here should be something like uh it is in buffalo that doesn't rally for peace okay okay so here are the categories and in buffalo is a prepositional phrase there right it's the rally for peace there okay uh and be be careful about where this attaches to resist the temptation to attach it to peace it's not a particular kind of piece that they were rallying for what we want is like generally they were rallying for peace and it just happens to take place in buffalo this rally okay so the other prepositional phrase is 4p so you could do something like the movement test so it was four piece uh that dozens rallied in buffalo something like that that works perfectly well and then right the relevant interpretation is that rallied for peace is what took place and so what we need to look for is this do so constituent so let's try this one okay dozens rally for peace in buffalo dozens do so in buffalo right and so now we obligatory like like clearly get the intended interpretation it only has one interpretation when you say doesn't do so in buffalo right and so something was happening and it took place in buffalo is the only interpretation that you get okay so that's definitely the unit that we want okay in buffalo tells you where this rallying took place and so you can try the do so substitution test again with the this entire big phrase and so dozens rally for peace and buffalo doesn't do so okay and then finally dozens is the subject and so you attach it to the end like this okay so this is the representation of the intended interpretation by this news headline okay so in one note about ambiguity um and so ambiguity is not inherently problematic because usually the context tells you uh like what the intended interpretation is supposed to be but sometimes it is a little bit tricky uh right with something like a news headline because that's the the first thing that you read without any context and so that could be a little bit confusing and so um this could potentially happen in like like your academic writing and things like that too if you're trying to you know make your writing a little bit more clear by avoiding ambiguity um there are some techniques to sort of like disambiguate your sentence i'm going to tell you that in case this is helpful and so for example if you wanted this particular interpretation for this sentence what you could do is like move the prepositional phrase around right and so if you actually like move in buffalo to the front you get something like in buffalo dozens rally for peace okay so that only has one interpretation which means that the rallying for peace took place in buffalo so that would be a really good way of disambiguating it so try things like movement if you're really trying to disambiguate it and it might be a better phrasing if you're really trying to avoid confusion in a context like this if you wanted the other interpretation where uh like the piece is in buffalo and that's what they want okay uh you could say something like peace and buffalo is what dozens rally for okay if it was a news headline to make it more news headline e maybe you could say something like peace and buffalo will they get it with this rally you know something like that where you know you can sort of isolate peace and buffalo as a constituent so that it's not ambiguous where the prepositional phrase is attaching okay so try things like movement uh whenever you are trying to disambiguate a sentence like this okay so structure help us explain sentential ambiguity like this right whenever you have a structural ambiguity in a sentence okay so i'm going to leave you with one more exercise okay um and so here is the sentence it is ambiguous spider-man memorized the digits of pi on that wall spider-man memorize the digits of pi on that wall okay so there are two possible interpretations right here okay and so i'm going to give you one of the interpretations one of the interpretations is something like this okay and so like there are digits of pi written on that wall okay and spider-man memorize these digits right that's the interpretation right here in this particular picture okay so your task right here is to come up with the other interpretation what is the other possible interpretation of the sentence okay and once you come up with the other interpretation provide the structure draw the tree for that interpretation so give the uh give the structure for meaning number two okay so pause the video and try this on your own okay you got it so there's a reason why i chose spider-man right here in this context right because the other interpretation is something like this right and so it's uh the meaning is like so make sure that the paraphrase that you provide for meaning two is a very clear disambiguation and so i said something like you know on that wall spider-man memorize the digits of pi right so remember i told you about like uh like movement to actually disambiguate something and so sometimes you can move um for example the the prepositional phrase to the front and you can disambiguate the sentence so on that wall spiderman memorize the digits of pi okay or you could say something like memorize the digits of pi is what spider-man did on that wall right and so the other strategy is to move the verb phrase itself to the front to disambiguate it so when you are disambiguating this the trick is to separate the prepositional phrase on that wall from digits of pi right because that's the other interpretation because the digits are pi are on that wall so you want to sort of separate those two somehow and so you could do that by moving the prepositional phrase itself or you can do so by moving the verb phrase to the front of the sentence so that would be a pretty efficient way of disambiguating and getting meaning number two okay so are you ready for the answer um okay so the critical constituent right here is the verb phrase in the middle spiderman memorized the digits of pi on that wall spiderman did so on that wall right that do so substitution clearly gets you meaning number two and only meaning number two so that's how you know that that's the correct structure for that particular interpretation so your tree should look like something like this okay did you get it okay if you have any questions let me know on discord or in the discussion forum but hopefully this is starting to make sense okay so that's it for sentence structure i just wanted to show you sort of the basic mechanism of how words go together in sentences okay and so if you're really interested in stuff like this with sentence structure um please take lin205 with me um because lin204 focused a lot on like word structure right so that's primarily what we worked on until uh this week and so lin 205 is a continuation of this course and we're going to sort of analyze sentence structure in more details we'll look at things like what different kinds of phrases do we have in a sentence and more about ambiguity what about complex sentences and things like that okay so definitely sign up for lin205 if you're interested in learning more about english from the sentence perspective and on that note this is actually the very last uh contentful lecture for lin-204 um and so there is no more new content in this class and so what's coming up is just your term test okay so what's going to happen is you're going to write your term test and then i'm going to upload just a couple of our videos after that for the very last week because we do technically still have class that very last week and so in those videos i just want to reflect on what we learned in this course and what you can do with the knowledge that you have acquired in this class okay and so let's do a little bit of a wrap up at the next time i see you in the lecture videos but until then i'll make sure that you do a lot of practice with the syntax tree stuff okay and so i've provided a lot of practice this time so that you can prepare for the term test okay um and so um let me know if you have any questions this can be a little bit tricky um and so also things like acceptability judgment so sometimes you do the substitution test and like maybe you're not sure if it sounds acceptable or not acceptable feel free to ask me does this sound natural in the english language acceptability judgment questions like that are completely okay to ask okay all right i hope you enjoyed learning about sentence structure okay i'll see you next time for the very last time okay bye you