Multiple overlapping genome regions can satisfy a given DNA sequenced-based CGI definition while their union does not.
Projecting these candidate CGIs on the DNA sequence yields a merged region that we call a CGI Shadow.
It not necessarily meets all constraints of the sequenced-based CGI definition, but each contained base pairs is at least member of one valid CGI.
The proof tracks below visualize this property by annotating the CGI Shadow, and the longest heading and tailing CGIs it contains.