Because the phrase "long pole is half as long as short pole" refers to short pole, and the phrase "short pole is half as short as long pole" refers to long pole.

According to the first sentence, it should be A=B+0.5B= 1.5B,

According to the second sentence, it should be b = a-0.5a = 2b,

So one or two sentences are logically wrong in mathematics.