Solution of one system in Boolean Variables via Mapping Method from USE Informatics test case as of 07/02/2020

Original system
(x1⊕x2) => (y1⊕y2)=1
(y1⊕y2) => (x3⊕x4)=1
(x3⊕x4) => (y3⊕y4)=1
(x1⊕y4) => (y1⊕x4)=1