If you can be sure that it will also be in the  <NPx> .. </NP> format, you can use this pseudo-code:

split the sentence on  <NP\d> and  </NP>; remove tags on the even elements; join the sentence elements again.

@parts = split(/<NP.*?>|<\/NP>/, $sentence);
$even = 0;
for $part (@parts) {
    if ($even) {
        $part =~ s/\/\w\w//g;
        $part .= '/NP';
    }
    $even = ! $even;
}
$result = join('', @parts);

[download]

Untested!

In reply to Re: How do I extract a text between some delimiters by fglock
in thread How do I extract a text between some delimiters by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.