three contigs are connecting by a black line, why?

[limin321]

Hi ,

Could any one please help me explain what does this visualization mean? the three contigs are connecting to each other by a black line, what does that black line mean?

I actually blast the middle contg against the longest, and it has 4 hits, each hits has 100% match, here is the mach results.

Does that mean I can just delete the contig in the middle.

However, I blast the top short contig against the longest contig and the middle one, there is no hits at all. if it is a complete independent contig, why they are connected by a black line.

Your help are greatly appreciated. Thanks a lot.

Have a good one.