Topology & Geometry - LECTURE 15 Part 03/03 - by Dr Tadashi Tokieda

to finish this whole course I'd like

to begin as I'd like to finish where we started when we first met I stood on a chair said hello and then started cutting a movie strip

remember so I'd like to show you two demos you've cut many of you have done the project even you've seen cutting a movie strip but a single movie strip here I have brought two ordinary

strips so they're not Twisted which I glued at 90° to each other is that clear let's cut each of these strips along the center line what do you think happens in order to think

happens in order to think clearly focus on the part of the picture which is at the Crossing of the two sheets okay and please imagine that

that direction goes in the back connects without a Twist and this direction comes in front and connect twist well cutting means that I take scissors pink scissors and then cut it along here and then cut it along here so

in the middle I cut in a cross what's going to happen well if I start going here I come there right where do I reappear here right not here because it's not twisted and

then I go there and then I come out from here the are you old enough to have played something called Pacman or is that prehistory for you but anyway so this goes out and then appears here and then disappears here and then I

come back here so how many pieces do we get one piece so let's see what we get do you have a guess we know that we are going to get one piece because we are good sign this but let's see what piece we

get two ordinary twists ordinary strips untwisted glued perpendicularly to each other yeah I'm now cutting one of the components one of the