2011/08/23

[28] For an ordered field K, ∀a,b∈K. a≦b ∧ c≧0 ⇒ ac≦bc, a≦b ∧ c≦0 ⇒ ac≧bc

http://www.evernote.com/shard/s29/sh/07b04633-3473-4674-a00c-dfe41ec62aeb/e6746a682987953882c5bf12a64b4e0b