# I write the following piece of code

**I write the following piece of code:**

x = var('x') assume(x,'real') y = var('y') assume(y,'real') z = var('z') assume(z,'real')

expr = abs(x-y)+abs(y-z) >= abs(x-z)

**The I run it:**
sage: bool(expr)
False

**The expression is obviously mathematically correct. How come Sage returns "False"?**