The tie theorems
  Theorem. There are general position points A, B, C, P on the projective plane. Let A_P be the intersection point of lines AP and BC. Analogously define B_P and C_P. Take any points A_1, B_1, C_1 on AP, BP, CP, respectively. Let W_C be the intersection point of A_1B_P and B_1A_P. Analogously define points W_A and W_B. Then lines CW_C, AW_A and BW_B pass through one point.   We also generalize this theorem and find interesting related properties. 
Roman Krutowski
math.HO math.MG