With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Chelsea F.C. is the first team to win all 3 UEFA club competitions.
text_B: The PlayStation 4 system software is the updatable firmware and operating system of the PlayStation 4 .. PlayStation 4. PlayStation 4. system software. PlayStation 3 system software. firmware. firmware. operating system. operating system. The operating system is Orbis OS , based on FreeBSD 9 .. operating system. operating system. FreeBSD. FreeBSD
not_related.