The projective geometry over partially ordered skew fields, II

In this paper «The projective geometry over partially ordered skew fields, II» the investigation of properties for partially ordered linear spaces over partially ordered skew fields is prolonged. This investigation was started in part I «The projective geometry over partially ordered skew fields». Derivative lattices associated partially ordered linear spaces over partially ordered skew fields are examined. More exactly, properties of the convex projective geometry $\mathcal{L}$ of a partially ordered linear space ${}_FV$ over a partially ordered skew field $F$ are considered. The convexity of linear subspaces has meaning the Abelian convexity ($ab$-convexity), which is based on the definition of a convex subgroup for a partially ordered group. Second and third theorems of linear spaces order isomorphisms for interpolation linear spaces over partially ordered skew fields are proved. Some theorems are proved for principal linear subspaces of interpolation linear spaces over directed skew fields. The principal linear subspace $I_a$ of a partially ordered linear space ${}_FV$ over a partially ordered skew field $F$ is the smallest $ab$-convex directed linear subspace of linear space ${}_FV$ which contains the positive element $a\in V$. The analog for the third theorem of linear spaces order isomorphisms for principal linear subspaces is demonstrated in interpolation linear spaces over directed skew fields.