Mtg 2/26: Thu-14-Jan-2021

Outline for Today

Wiki

Link to the UR Courses wiki page for this meeting

Media

Transcript

Binary Guessing Game

• Think of a number between 0 and 15 and I will guess your number by asking you 4 yes-or-no questions (I've added some links that explain the game in more detail). It is easiest to ask those questions if I have cards to show you, so let's talk about how to make those cards.
• May I read your mind?
• Binary guessing game activity
• A guessing game





NEXT CARDS

We have discussed how to make 3 cards. How does the table get extended with Y's and N's if we make 4 cards and if we make 5 cards?

FLIP THE CARDS

We have discussed making cards with Y's from the table. What happens if we make cards from the N's? How can a guess be made from these cards?

Encoding

ENCODING

Use of "a system of rules to convert information — such as a letter, word, sound, image, or gesture — into another form, sometimes shortened or secret, for communication through a communication channel or storage in a storage medium." (Wikipedia)

• Character encoding
• Code
• Encode



• ASCII
• Unicode
• UTF-8

Puppy

Elgar stars in commercial along with one of his litter mates

Zoom Audio Transcript

• Hello everyone. So I have a bit of a family thing going on today so I make it a phone call. And then we'll end the meeting a bitch. You might end the meeting. Early today. Okay. I do have a video of my puppy. Chasing his tail. Works later on. Okay, so Everyone's 19 so I'm not sure whether the other people in the class. Anyone, anyone lose your power last night. No. Apparently some people did well versed I had Some flickering lights. Lot of wind that Is scary for the puppy and And for me to actually mean it. Tree big tree outside the window here is Being bent So scraping the house and say, gee, I probably wouldn't be good if a branch broke off. Anyway, So enough about that. Okay, so for First things first. Video of puppy. I think Discovering that the occasionally discovers he has a new toy. There with him. This do that once your senses so short. Okay, so that's all These see Is about 12 weeks old. Now we got them supposed to be all 10 weeks old. Two weeks. And I Can week From this Sunday, which is almost two weeks past so He's mostly adorable. Now it's completely adorable but sometimes he acts like a puppy. Anyway, okay, so there we go. Now you've met him. Have you'll get a show you a video from time to time. How easy Because by the end of the semester, he won't be so so puppy like System of getting email before each day. So I'm inclined to think that maybe I will just create a meeting the zoom meeting for the whole semester. So we don't have to keep going through Emails, and then I can just post it in the calendar. Any thoughts about that. Seem like A smoother solution. To be paranoid so well. Just because I'm paranoid doesn't mean people are aren't out to get me. Someone heard that before. Okay, so I'll created A link a recurring meeting link for Our class meetings.
• Me.
• See video link on our Meetings page. Alright. Well, Let me go back to So from So I worked out a way to present the summary, but I didn't. fill in the details or summary so The idea is for the transcripts of the audio and the chat. I will Use my discretion to come up with topics here. That we discussed like welcome. If you click on the topic and you can hide the details. And then I'll put in Various points here and I'll add links as appropriate. So So for example, we talked. I'm going to add the link for the CS web page. Building instructions. That's one of the things we talked about Anyway, So that was last day and then So I didn't I'm still working things out here a little bit. But then the notes for two or five meeting to Now, take it to the video. Where's the thing they won't always be videos, but maybe a links to look through and so forth. Try various say Maybe preparation or something, instead of notes so it can be an unknown location. Let me just make sure that it's there on the website. On the public website this is on my laptop when it's local host Does anyone here use the static site website generator So I'm using jackal. Well that's nice. Sorry, not that nice. You haven't used it yet, but I see that the when you're on your camera view you say no or yes or something and it pops up on the over top of the video. So that's very Very handy. I'm impressed with the zoom for that feature. I can't get a whole list of people Anyway, Okay, so this is the web page on On the public CS Department web server side. There. Today, when I had the chance to look at that already. Okay. So look at this over the weekend and then we can Talk about it next day in more detail. So the idea is That information entropy Like the third law of thermodynamics, entropy In some ways it is in some way that's not to me. I find it interesting that you talk about the entropy and information as measuring surprise. So if you think of tossing a coin. If it always lands on heads. Not necessarily a coin. For one thing, They're also not very much surprise in it. So if the odds of Getting ahead and getting a tail or equal at 50% then there's as much As we can handle from From that one coin. And So that's So we have two outcomes from flipping a coin zeros and one or heads or tails, which you can think of the zeros and ones. Which leads us to the Idea of a binary digit or best And so I'm going to Impress you quote unquote with my drawing skills in a minute here. I thought I don't have a video of this And I don't have The props with me. So I'll dress and I'll draw it out from the beginning, from the ground up. So this is going to be about An application of of Of encoding to represent different Different quantities. So if we look at A single bit. How many guys. Can we encode with that. You're welcome to use your microphone. And if you want to just unmute yourself for a bit, you can press the spacebar, I think. That's failing that, I will get out of my chat window. There's a question. Yeah, so Much. So another way to say it is how much information you know so we have to do is zero and one. And that's why, computer scientists like to start counting with zero Or the first array indexes zero Right, because precinct of Representation of it. If we say, off and on. So those two values us Euro and one Okay, so how many if we get to bits. How many values, can we represent. Okay, and how about three bits. Know 16 is four bits. All right. And 32 is five minutes. Yeah, that's right. So it's, it's an experience. So two times two times two were two to 38 Oh, you're just you're anticipating my question. That's very good. I can see you. Laughing I can hear you. Laughing So, That's Kind of a nice way to Experience it so that's That's eight bit. No. Yes, eight this is 256 OK, I can count so eight and 910 Okay. All right. Okay, so this is this is a lot of fun and we can go on to So we get the idea. So is anyone heard the story about The fellow who Who did a fair for the king and for the reward. King said Nate name which you'd like. He said, I'd like one grain of rice to put on This first square the chessboard And then The next square and have it doubled and then doubled again. It's all. Okay, sure. But by the time the chessboard is full. That's quite a big number, isn't it. So, You know the bit a bit can only store two values and put them together. In store lots and Lots of values. So, Without getting too philosophical there. Let me Sorry, bear with me for a second. I tried to get this working in rehearsal. Time. Okay, let me Try another thing here. I really better be worth it if I'm gonna Okay, made some progress here. Okay, so This is a Binary guessing game. Maybe you've heard about it. So, Okay. Okay, so if there's a One bet we can set us in the zero position. And we can say no. Or yes, So vs revalue here. Okay, let me back up and give you the context. So our binary guessing game. That I have available. Which I should make the materials available online somewhere. So you can see this and all its glory. So in that in the setup that I use. Generally, I have four cards. And a card that represents the one position. The two position before position and the position. So let's say I just had one card instead of four. So one card. And so The idea is to show that I have ESP extrasensory perception. Perception, I say, Is your number on this card and you say yes or no. So if I'm going to have one card. And I'm going to guess your number. Two. The card is going to have the number one on it. So what other constraints. So, what, what's the range of numbers. You can guess you can pick, I can guess. I'm sorry, I should have I got thrown off by the technology here a little bit, but
• In this case, our options if I'm understanding you correctly would be one or zero as our number so Either way to say yes or no. You're going to know what our number is
• Yeah. That's right. So if I say pick a number between zero or one, zero and one. Pick a number either zero or one. And I show you the card with the one on it and you say, Yes, that's my number. And if you say no, that's not my number. Then I take the card and put it to my head and say, After some theoretical part theatrical pause I say this as the psychic energy travels from you to me. And I say, If you answered yes to that question your numbers one and if you answered no, that your number 01 card. Okay, now if I have two cards. What I'm going to do is Different combination There's two cards we have twice as many values possible Sorry. I have to make a little correction here. Alright. No, no, and we have To but no one. So then we have To end if we ever yes and yes it's a two and a one is three. So this Is the classic. How many different kinds of people are there in the world. If you It's funnier if you see it written out if there are one, zero kinds of people in the world. Those who understand binary and those who don't. Because one zero yes no is is equivalent to decimal to Because you can only represent one up to one with one between you. The second bit To represent The value of two And then if we have yes and yes three Two cards. Okay. Why don't you tell me I'll get my chat window open here again. So what are the numbers that we're going to write on one of the cards. OK. So the reason Is a nice a nice number Nothing against it. The reason I would vote, I would not choose that one is because
• It.
• If I'm if I'm asking the question, Is your number on this card. And it's it and we have a number that is a zero. So that would answer. No, no. And it gets confusing. So what I'm gonna say is We put the From one column one in three Two and three No, that's not right. So if this is the card. I'm showing one three your answer yes to this. And then I show you the next card, which is two, three answer yes to this and what is the number going to have to be You have to be a three because you said yes to one and yes to the other. So the way we figure that out is Two plus one equals three. And we can see that if we say yes to both cards, the only number that appears on both of them. Is the three This let's do a three cards and then that should Be enough torture with this thing. I don't mean to create torture. I don't want to create that idea. Okay, so I saved that one. So I'm going to erase A little bit of this. OK, so now for a third card. We're going to write in
• Pencil
• Alright, so adding a know in this third position doesn't change any of the existing values. So we still have 0123 But now let's copy everything down. And then for this one are going to Change the intro for change. The no to. Yes. Okay, so without These next word numbers. So we can figure that out. In a few different ways. Yeah 4567 So what we're doing here really one way, if it's helpful to think about it is taking these values and heading for to them. So zero plus four is for One plus four is five. To two plus Three plus four, seven. Consciously Yeah, so We can just go by. Each call If we say each column is a card and we just record designers have yeses beside them. In the values where there's a yes. So, for Six. Seven. And then for the to The next card to 367 And then we have One, three, Maybe too far down in the screen. I don't know what's going on here. Okay, so these are the three cards and I say to you get guess an hour between zero and seven. So how does this. How does this work in practice. So you have cards with these three these three cards with These sets of numbers on them. So can you explain how how to run the trick. To prove to unsuspecting grade school children that you're having Extra Sensory perception. Anyone's welcome to turn the microphone on for them.
• So in this case we can assume that someone got for, for example. So when we show the first card. We would ask, do you have a number on the first part. So they have the Fort Detrick, they would say yes. So for us, we would know that the number is either four or five, six or seven And then next card and then for the next one, they would say no, definitely because the four is not there. So we know that six and seven cannot be the option we eliminate those two Then we go to the next card and they would say no, what's not on there too. So we are limited to five and then we can do that. It's
• Okay, that that's That That's a very good explanation.
• The question though. Does that work the same. If we use the positions of the zeros instead of the ones right Like the yes the nose, instead of the yes
• Yeah. That would Be an extra level of indirection for people to say, So then, then you'd have And the third card, it has 02402460145 And 0123 trying to get my head around. To doing the tables. And this is all kind of like, well, it is math on the board for me. Yeah, so that's right So we could do things. Change it up and put the put the Nose yes and yes no and make a little more interesting for set of cards. That brings me to a point that it's a good segue into A topic about encoding. Let me just first say about the way to think about this. So if we have the cards. These three cards set up. With a forum on the top and to the top and one of the top If we make note of what's the number on the top number on the card or a free Print out a make a note on the back with the number is the top number is So if we say yes, no, yes. And we have four plus one. So if we have a yes who started out in this way, we started our guests at zero. And for every yes to a card we add the value we add to the first value on the card. So this card is yes, and we add four to zero. So we have four to start with. And if we say no to this card. We don't add anything, and if we say no to this card. We don't add anything And so if they say yes to the four card. Then we Pass dramatically and say your numbers for You can work out the instructions, if you if you flip it between The show the zeros to the Card be the 0246 And so far. Anyway, I'm getting I'm getting Work. Anyway, Alright. So that makes sense. First of all, so the idea is that we can have We have Three best we can store. And then the idea is necessary that we have to Don't have to store. We could say it's durable. We can also say it's 28 So we're going to store different values. So we can use this technique. We only need to store. Restore the index values here. We go. We only need three best to do that. We can storm. We can have a reference larger values. And that's what's done in images. For example, and we'll talk about it later. So if you have a We have 256 Spots to different guys you can represent So we can have them represent grayscale value. We can represent raise your turn black and white. Is a Fraction on that continuum, or we can use those value. Where we can have We can have each value reference look up into a table of full color. So, When when space is more of a premium. We could do this trick by storing on the eight bits. For the pixel dies. But then, having us. 236 index nice looking like of into a table that would We would have a palette of 20 256 colors. So we could have a Rich colored image. That have very little storage without the need to have Store each row is 24 bits. What time is it 10 minutes left. Okay. So we need more than three best represent Characters in the English language. Right. So we could we would need at least Values. So we could encode the characters in the text. So that would let us do the capital letters, plus a little bit of punctuation maybe Which which is a sci, which stands for American Standard Code for Information Interchange Someone pointed out that it's really know the American national Standard well anyway. We don't really talk about ASCII too much anymore directly. We talk about UT F8.
• pretext.
• Okay. Which is skipping ahead a little bit So we're going to talk about ASCII and Unicode ETFs eight is a way to represent Unicode In a compact way. Store ASCII We don't even use 888 that would give us 236 more Me because another hundred and 20 character positions. Because asked good for North American English. Not even Now even all the variations of English. With the different symbols and so an accent. So we'll talk about that in more detail what happens If we try and get more characters out of ASCII by using the eight bit And then That may be a good start, but it doesn't really get us very much for that and we As far as we need to go so Unicode is based on a form that form bite. So eight bits, the bite. So one bite for asking or it to a portion of a bite for ASCII And the Unicode is for by So that gives us a lot more potential But we don't have anyway. So there's some complications involved, and we'll talk about them in the next Next week, So if you can have a look at that video I posted And I'll post some other videos as well before Tuesday. Okay, and it will get your courses. Set up so So we'll start in earnest, with the attendance and then engage with us meetings. Tuesday. Okay. Okay. And I'll figure out how to better uses technology. See what What Zoom is telling me to do and what wasn't doing for me on my iPad. Anyway, Never a dull moment right so stay well. And we'll keep warm and Have a great weekend. And we'll talk to you on Tuesday. And I do have some office hours coming up. Well, I have an officer at 334 30 today. And Otherwise you can send me email or push to the forums and I'll get to them. So with that, I'll say goodbye. Thanks for today and we'll talk to you soon. Okay.

Zoom Chat Transcript

• hello
• HII
• Hello!
• yup
• yup
• Yeah
• Yup, for a while.
• My security system went haywire and I ended up using ear plugs all night
• until powere was officially on
• *power
• my power didn't go off but my building decided to lose a lot of its siding, shingles, and outside support lol
• PUPPY
• What is your puppy’s name?
• Cute dog!
• VERY CUTEEEEEEEEEEEEEEEEEE
• adorable
• Yeah that would be Great!
• yes please
• That would be better
• that'd be good
• Yes please
• sounds good.
• Definitely smoother
• I like having one book marked zoom link
• ya it would be better
• Either is good but having one consistent link is nice
• that would be great
• instead of clicking stuff
• the zoombomb in winter 2020 was partially due to the classroom links not needing anyone to sign-in to view the links
• if it's posted in URCourses it should be fine
• I agree @emily
• yep
• yes
• no
• i'm sorry, i missed the question.
• what was the question? I missed it too
• how many values can 1 bit hold?
• 2
• 2 values - 0 and 1
• on and off
• 4 values
• 8
• 16?
• 8
• 8 values
• 8
• 32
• 2^3=8
• we are just answering in advance :)
• haha
• 256
• 512
• 1024
• 2048
• 2048
• 2048
• 4096
• 4056
• 2^32 = 4294967296
• 1e+10^9999
• i vote for 00
• 01
• 0 and 1
• 0 and 1
• 1
• 3 and 0
• 4567
• card1: 4 5 6 7 card2: 2 3 6 7 card3:1 3 5 7
• Each card has a column of yesses.
• yes it does
• 0 - 127
• Have a nice weekend!
• Thanks, you too.
• Thanks!
• have a great weekend!
• thank you
• bye
• Thank you. Bye
• Bye Sir
• Have a good weekend

Responses