sub compatible { 
    my ($s1, $s2) = @_; 
    y/_/\0/c for $s1, $s2; 
    !(($s1 | $s2)=~y/\0//); 
} 
print(compatible("_8__3__19", "48_____7_") ? "true\n" : "false\n");

##</code><code>##

sub compatible {
    y/_/\477/c, y/_/\0/ for my @m = @_;
    !((($_[0] ^ $_[1]) & $m[0] & $m[1]) =~ y/\0//c);
}

printf "%s v %s ? %s\n", @$_, compatible( @$_ ) ? 1 : 0
        for [ qw[ _8__3__19 48____7__ ] ],  # compat
                [ qw[ _8__3__19 4_8___7__ ] ],  # compat
                [ qw[ _8__3__19 48_____7_ ] ];  # clash