Terrible spec: title and body content conflict. - -, and then change, repeatedly, in later nodes.

Working from the title, however,

#!/usr/bin/perl
use strict;
use warnings;
# 794700

while(<DATA>){
        # if($_ =~ m/\bpublication date\b/){
    if($_ =~ m/\bpublication date\s/){
    print $_;
    }
}


__DATA__
These are the dates.
The publication date is 20-10-09
The publicatiion dateee is 20-05-08
The publication dat is 10-06-07
The publication date's are 20-10-09,29-02-08
[download]

Output with \b after "date" (incorrectly accepts "date's" which should be "dates" in this --plural-- context.)

perl 794700.pl
The publication date is 20-10-09
The publication date's are 20-10-09,29-02-08
[download]

Output with \s after "date"

perl 794700.pl
The publication date is 20-10-09
[download]

If one wishes to accept both "date" and "dates" (eg:

The publication date is 20-10-09
The publication dates are 20-10-09, 29-02-08)
[download]

alternation could be an answer:

if($_ =~ m/\bpublication date\s|\bpublication dates\s/){

Please see perldoc perlre (perlre) and company.