In the Euclidean plane, lattices can only have exact rotational symmetry under rotations of 180, 120, 90 or 60 degrees. In the Lorentzian plane, lattices can be constructed that are symmetric under “boosts” with parameter arccosh(n/2) for any integer n>2. For this lattice, n=3.
#tbt that time in 1983 a friend and I did some feminist graffiti because we thought there wouldn't be any police out on Christmas Day (we had literally just put the spray can away when a police car drove by)
We aim to celebrate St David’s Day by reaching 2,000 followers. Please help us get there by retweeting a very Larkinesque A-sign outside Hull charity shop.
We'll be 20 next month and we're celebrating this in a number of ways… for now though I just want to tell you that we're accepting submissions through March from previously unpublished writers - stories and poems. Do please help us spread the word. #Fly20
https://t.co/h9dTbSKe1x
Blog | A lifelong devotee of the works of #VirginiaWoolf, @adrianmasters84 experiences the rare sight of Vanessa Bell and Duncan Grant's legendary Famous Women Dinner Service on display in London.
https://t.co/y2kE7G8hcl
Time & Snow - does time slow down, or speed up, when you're snowed in? One for Sean Enda Power @jdepaor or anyone else with 6+ inches of snow outside the door... @hayfestival@dubcilib