Is Birkhoff-James orthogonality an orthogonality in the sense of Ratz?
Orthogonality in the sense of Ratz:
Suppose $X$ is a real vector space with $\dim X\geq2$ and $\perp$ is a binary relation on $X$ with the following properties:
Totality of $\perp$ for zero: $x\perp 0$ and $0\perp x$ for all $x$;
Independence: If $x,y\in X-\{0\}$ and $x\perp y$, then $x$ and $y$ are linearly independent.
Homogeneity: If $x,y\in X$ and $x\perp y$, then $\alpha x\perp\beta y$ for all $\alpha,\beta\in\mathbb{R}$.
Thalesian Property: If $P$ is a 2-dimensional subspace of $X$, $x\in P$ and $\lambda$ is a nonnegative real number, then $\exists$ $y_0\in P$ such that $x\perp y_0$ and $x+y_0\perp \lambda x-y_0$.
Birkhoff-James orthogonality:
$x$ is said to be Birkhoff-James orthogonal to $y$ if $\|x\|\leq\|x+\lambda y\|$ for all $\lambda\in\mathbb{R}$.
I could figure out that properties 1, 2 and 3 of Ratz's conditions for orthogonality are satisfied by Birkhoff-James orthogonality. The last condition bothers me.
Question. Is Birkhoff-James orthogonality an orthogonality in the sense of Ratz, or not?
Thanks in advance!