Published online by Cambridge University Press: 20 November 2018
Let   $\alpha $  and
 $\alpha $  and   $\beta $  be two Furstenberg transformations on 2-torus associated with irrational numbers
 $\beta $  be two Furstenberg transformations on 2-torus associated with irrational numbers   ${{\theta }_{1}},\,{{\theta }_{2}}$ , integers
 ${{\theta }_{1}},\,{{\theta }_{2}}$ , integers   ${{d}_{1}},\,{{d}_{2}}$  and Lipschitz functions
 ${{d}_{1}},\,{{d}_{2}}$  and Lipschitz functions   ${{f}_{1}}\,\text{and}\,{{f}_{2}}$ . It is shown that
 ${{f}_{1}}\,\text{and}\,{{f}_{2}}$ . It is shown that   $\alpha $  and
 $\alpha $  and   $\beta $  are approximately conjugate in ameasure theoretical sense if (and only if)
 $\beta $  are approximately conjugate in ameasure theoretical sense if (and only if)   $\overline{{{\theta }_{1}}\,\pm \,{{\theta }_{2}}}\,=\,0\,\text{in}\,\mathbb{R}\text{/}\mathbb{Z}$ . Closely related to the classification of simple amenable
 $\overline{{{\theta }_{1}}\,\pm \,{{\theta }_{2}}}\,=\,0\,\text{in}\,\mathbb{R}\text{/}\mathbb{Z}$ . Closely related to the classification of simple amenable   ${{C}^{*}}$ -algebras, it is shown that
 ${{C}^{*}}$ -algebras, it is shown that   $\alpha $  and
 $\alpha $  and   $\beta $  are approximately
 $\beta $  are approximately   $K$ -conjugate if (and only if)
 $K$ -conjugate if (and only if)   $\overline{{{\theta }_{1}}\,\pm \,{{\theta }_{2}}}\,=\,0\,\text{in}\,\mathbb{R}\text{/}\mathbb{Z}$  and
 $\overline{{{\theta }_{1}}\,\pm \,{{\theta }_{2}}}\,=\,0\,\text{in}\,\mathbb{R}\text{/}\mathbb{Z}$  and   $|{{d}_{1}}|\,=\,|{{d}_{2}}|$ . This is also shown to be equivalent to the condition that the associated crossed product
 $|{{d}_{1}}|\,=\,|{{d}_{2}}|$ . This is also shown to be equivalent to the condition that the associated crossed product   ${{C}^{*}}$ -algebras are isomorphic.
 ${{C}^{*}}$ -algebras are isomorphic.