## oliver knill

- Quotient Rule t.co/SDWJzFZ7rY via @YouTube
- In Python, "for n in range(20): print(2^n);" gives the BitXOr sequence 2 3 0 1 6 7 4 5 10 11 8 9 14 15 12 13 18 19 16 17. In Mathematica: Table[BitXor[n,2],{n,20}]. The graph of BitXOr[n,m] is a nice Sierpinski pyramid Plot3D[BitXor[Floor[x], Floor[y]], {x, 0, 31}, {y, 0, 31}] t.co/Rj5Hd61PCK
- Just configured a dream configuration of a new Mac Pro: 28 Core 4.4 GHz CPU, 768 Gig RAM, Two Radeon Pro graphics cards, 8TB SSD, Afterburner. Only 53447.98 Dollars. And sweet, the Power cord is included .... t.co/OFK55RO4Y7
- A new picture of George Lowe t.co/7llT6BBc3f who made some pictures motivated by Kempe chains t.co/o5eJECLo6Y appearing in graph theory. The actual picture is 8 feet wide and called "Anemone of the State". (The picture is ditributed by permisssion of the artist.) t.co/OtLjHf589E
- Welcome 2020, the Pecha Kucha year! t.co/E3062o6pXE Pecha Kucha is a presentation form where 20 slides are shown 20 seconds each. A tough way to present as it needs lots of preparation. We experimented with it once 6 years ago in the department: t.co/DyHosWjtPK
- The Betelgeuse in Orion is exciting as it might blow up in the next 100'000 years or so. Excitement due to some unusual dimming: t.co/8cFFlffyVG Wouldn't it be nice if we could see it explode in our life time? Just took a smartphone picture to make sure it is still there. t.co/kBY1nq1VIB
- How many meaningful sentences of length k are there with words div, grad and curl? f(1)=3,f(2)=5,f(3)=8 (a 21a exam problem) and f(4)=13. It is Fibonacci number f(k)= F(k+3): proof: a digraph encodes all possible transitions. Use linalg to count. TikTok: t.co/hgSSgxIcss t.co/dRixduhncR
- Some mathematica projects from the Math 21a fall 2019 course: t.co/I2EDaluBVS and t.co/HL5peqq3H8 Creative class! It is a general fact that many students do not know their creative potential until they try it out. t.co/k5X3YwleY6
- Some footage of the Mathematica workshop from Thursday afternoon t.co/F3GJ5oFRhP Quit nice 4K quality delivered by a go pro 7 camera. Better than the Go pro 3 from 5 years ago in 2014: t.co/hl5gHKFjsV
- Poincare-Hopf for graphs t.co/0gOuMtKhrL can be generalized to irrotational digraphs (there are no cyclic triangles in the digraph). The theorem tells that the sum of the P-H indices i(x)=1-X(S^-(x)) is Euler characteristic X(G). See t.co/0gOuMtKhrL Examples: t.co/PvVncig3gc