Point (a,b,c) meaning (a/c, b/c) Line (a,b,c) meaning ax+by+c = 0 Point x Point = Line Line x Line = Point
v-e+f = 2
area A, interior points I, boundary points B: A=I+B/2-1
nimber = mex{possible states}
Moore's nim: Remove something from at most k rows. Convert to 2-base digits, treat each digit as k+1-base digit. Add without carries. (eg. xor is add-without-carry in base 2)
misere nim: play exactly as if you were playing normal play nim, except if your winning move would lead to a position that consists of heaps of size one only. In that case, leave exactly one more or one fewer heaps of size one than the normal play strategy recommends.