I have following paragraph and trying to understand what it clearly mention.

This paper shows several extensions and discusses the topology

approach, while recognizing that reconstruction of height jumps is a

challenge (A, 2010; B, 2007) and describing problems related to

intersection lines and jump edges between two segments.first sentence is clear to me. I have problem with while part. It contains that also. So, I am confused. I want to know this and describing.. is related to that or while.

If I simplify my question,

Does the stricture of second part is

- while recognizing (X) and describing (Y) or..
- while recognizing that

(P and describing Q).

UPDATE:

If I like to modify 1, Would it be possible to use one recognition as while recognizing (X) and (Y). I think yes, But Y is too long, Does this misguide the reader?Can anyone help me to get the idea of this. thanks

**Answer**

The structure of the second part is:

- while recognizing (X) and describing (Y)

For clarity:

This paper shows several extensions and discusses the topology

approach, while (1) recognizing that reconstruction

of height jumps is a challenge (A, 2010; B, 2007), and (2) describing

problems related to intersection lines and jump edges between two segments.

**EDIT**: For your second question, I think you’re asking for this:

This paper shows several extensions and discusses the topology

approach, while recognizing that (1) reconstruction

of height jumps is a challenge (A, 2010; B, 2007), and that (2)

problems related to intersection lines and jump edges between two segments

are also challenges.

Note that in the above paragraph, I have added **“are also challenges”** to the end of (2) in order for the fragment to make some sense.

**Attribution***Source : Link , Question Author : gnp , Answer Author : Chris Mukherjee*