Correction for HW1

We found another mistake in HW1.

3.(a)(iii)

wrong: Is this open in R2? Is this closed in R2?
↓
correct: Let define A={x in R2 | a < x1 < b, x2=0} Is this open in R2? Is this closed in R2?

Thanks Kubota, Takashima, and Fukuda for letting me know.

For precise description, please refer to this.

Kohei