# Yossi Elran

I'm a recreational mathematician and metagrobologist and head our institute's technology in education unit. I have a Ph.D. in theoretical quantum chemistry, and think math and science are really cool!

Location Rehovot, Israel

## Activity

• You're not thick at all @LeslyeSlater ... I take the blame for not explaining clearly enough. Thanks @LawrieBrown for doing a much better job than I have done...:-)

• Wow! Fantastic! @LawrieBrown

• Point flexagons are vertex flexagons... The pats hinge at the vertices of the triangles. Scott Sherman and others are working on a fundamental theory but it doesn’t look like it will involve group theory...

• + and -

• Yes - and in fact that has happened - Scott Sherman has found new flexes through his computer program!

• At a glance it looks correct! Good for you!

• Thanks for spotting that error !

• No - it's difficult to see the structure of the flexagon on picture 6 on the previous state - it has much more inner structure. The three sector fundamental first order square net can create two flexagons. One that in its main position is skewed (and doesn't lie flat), and the other that is a box. The net above has two sectors. The three sector version has a...

• Thanks @OlenaKryvtsun for spotting that error!

• The normal mode chart shows the states of the flexagons that are accessible without inverting the strip using the wormhole flex.
There is no special meaning to the letters, numbers or even order of columns and rows, except that the first four columns are states formed by twist flexing, the last four columns the patterns on the other sides, and alternating...

• LOL!

• The short answer is yes. But - to remove ambiguities - flexagons should be constructed with a stable main state. If, when they are first discovered, a more stable state is found when flexing, the flexagon construction instructions should be changed to make this new state the main state. Of course, in practice, this does not always happen...

• Good idea! They are theoretical, but, like many things, can be approximated by expanding the "point" connection to a very small linear hinge. I am not a great fan of vertex polygon rings, but I thought it important to include a mention of them so that if people encounter them, they'll at least have a clue of what they are.

• Thanks!

• Thanks @LornaAllen ! A good point... If I have time to redo them...

• @InekeFioole Thanks!

• @LeslyeSlater It should read "bottom leaf hinged to pat..." - try reloading or clearing the cache...

• Yossi Elran replied to David Webb

The answer is - not yet, really. But then, that's how many good inventions started...

• How very alert you are! :-) You are of course correct! Benjamin Franklin's magic squares - known as Franklin squares - do not add up to the magic number on the main diagonals - but they have other interesting properties which you can read about here: http://recmath.org/Magic%20Squares/franklin.htm

• My mistake... thanks for spotting that. I've corrected the text...

• Only by modifying the script language - this is beyond the scope of the course. However, the program should color the leaves "correctly" - though there is still some debate what "correctly" means on some of the more complicated flexagons...

• The main hinge is the hinge you are using for the flex. In some cases there are more than one - for example the pinch flex on the tri-hexa-flexagon. Because of symmetry in this case it doesn't matter which of the three you choose as the "main" one.

• Yes - you should receive an email with links to the recordings shortly @RuthEstrella-Pinto

• @InekeFioole Sorry to hear about your husband and thank you so much, not only for taking the course, but for being so active and stimulating so much conversation! Take care!

• Yes - you should receive an email with a link to the recordings shortly

• Yes!

• Making a video is a good idea - Thanks - I'll try to fit it in to my schedule.

• Thanks!!!!

• My pleasre @PaulC I'll be sending out an email with a link to the recordings later on this week

• There are two flexagon templates - one that turns into a heptagonal flexagon and the other a hexagonal flexagon - the numbering has no real meaning - just a way of indicating to those who downloaded or bought the full booklet which template we're using...

• There are a few posts on Facebook... Not many people on the course seem to use social media but don't let that put you off... :-)

• Yes - my mistake - thanks for spotting that - I've fixed it...

• @LeslyeSlater We'll have about up to 45 minutes...

• Yossi Elran made a comment

So I've reread all your comments, and seeing as it seems that you have quite a lot of questions, by popular request I am happy to tell you that I have managed to arrange two more Zoom sessions this coming Thursday July 1st. One at 10:00 am Israel time (8:00 in London, UK, 9:00 in Madrid, Spain, 17:00 in Sydney, Australia). The other at 21:00 Israel time (14:00...

• Yossi Elran made a comment

So I've reread all your comments, and seeing as it seems that you have quite a lot of questions, by popular request I am happy to tell you that I have managed to arrange two more Zoom sessions this coming Thursday July 1st. One at 10:00 am Israel time (8:00 in London, UK, 9:00 in Madrid, Spain, 17:00 in Sydney, Australia). The other at 21:00 Israel time (14:00...

• Yossi Elran made a comment

So I've reread all your comments, and seeing as it seems that you have quite a lot of questions, by popular request I am happy to tell you that I have managed to arrange two more Zoom sessions this coming Thursday July 1st. One at 10:00 am Israel time (8:00 in London, UK, 9:00 in Madrid, Spain, 17:00 in Sydney, Australia). The other at 21:00 Israel time (14:00...

• Yossi Elran made a comment

So I've reread all your comments, and seeing as it seems that you have quite a lot of questions, by popular request I am happy to tell you that I have managed to arrange two more Zoom sessions this coming Thursday July 1st. One at 10:00 am Israel time (8:00 in London, UK, 9:00 in Madrid, Spain, 17:00 in Sydney, Australia). The other at 21:00 Israel time (14:00...

• Yossi Elran made a comment

So I've reread all your comments, and seeing as it seems that you have quite a lot of questions, by popular request I am happy to tell you that I have managed to arrange two more Zoom sessions this coming Thursday July 1st. One at 10:00 am Israel time (8:00 in London, UK, 9:00 in Madrid, Spain, 17:00 in Sydney, Australia). The other at 21:00 Israel time (14:00...

• So I've reread all your comments, and seeing as it seems that you have quite a lot of questions, by popular request I am happy to tell you that I have managed to arrange two more Zoom sessions this coming Thursday July 1st. One at 10:00 am...

• I really can't understand it then @SuzanneByrne... In my browser the template and the video are the same! Since the problem was with the video - can you perhaps pause the video and take a screenshot of each side and email it to me along with your downloaded template so I can try and figure this out? My email is: yossi.elran@weizmann.ac.il

• Yes!