How Many Holes Does a Straw Have?

So, according to Riemann, because a straw can be cut only once — from end to end — it has exactly one hole. If the surface does not have a boundary, like a torus, the first cut must begin and end at the same point.

Is a straw 2 holes?

If a hole is defined mathematically, like a torus shape, then a straw has one hole.

Does a straw have 2 holes topology?

The mathematically correct answer is 1 hole. A straw is topologically the product of a circle, which has 1 hole, and an interval, which has 0 holes. So the straw has 1 hole. ... Intuitively, we can agree a circle has 1 hole–the simple closed curve contains a 2-dimensional hole inside of it.