There's something missing in that solution, or I don't understand it. I'd have expected something like:

use strict;
use warnings;

my $abc = 'AABCBAABCCCCAB';
my $yes = 'AABABAABABABAB';
my $no1 = 'ABBABAABABABAB';
my $no2 = 'ABBABAABABAB';

$abc =~ tr/AB/\0/c;

print +(($abc & $_) eq $abc) ? "$_: yes\n" : "$_: no\n" for $yes, $no1
+, $no2;
[download]

Prints:

AABABAABABABAB: yes
ABBABAABABABAB: no
ABBABAABABAB: no
[download]

The test fails if you change all the Bs to Es of course.