[masaegu]

Originally Posted by chryuop

I know the fact that は is used in a comparative way, but what puzzled me is that the dictionary says that in Japan most of the times one of the the 2 parts compared is missing (given for granted). It gives a few examples like 子どもには無理だ giving for granted a missing part which could be 大人には出来る or again 大阪までは行ける giving for granted something like 大阪から先は行けない.

This is true. Something is implied when you use では、には, etc. You don't have to say the second part to be understood.

Does that mean that if I want to say a phrase which has a "but" hidden in it I can use は? I mean, for example if Masaeguさん is talking to me in Japanese I could tell him 聞いてはいる giving for granted a phrase like 聞いてはいるが、分かりはしない? (hoping that he doesn't understand I am listening to you, but I don't care...it could be misleading when 1 of the phrases is given for granted).
But at this point, wouldn't the use of は carry a negative meaning when used (except when used to introduce a topic).

Yes, you can use は again for emphasizing the negation if you want to, but it isn't necessary for getting your idea across. Native speakers would usually use the は just once.
聞いてはいますが、分かりません。

Another little question about one of the examples: ゆっくりとは読めても、すらすらとは読めない小説　I think I have no problem about the meaning which should be "even reading this novel slowly, I cannot read it smoothly"...but my question is about the use of は. I was taught that は cannot be used in subordinate clauses...and here they are subordinate because modifying 小説. :O

You are somewhat misunderstood.

In the relative clause 「ゆっくりとは読めても、すらすらとは読めない小説」 , the は is NOT being used as a subject marker. There is no subject mentioned in the mini-sentence within the clause in the first place.

If it was 「スミスさんがゆっくりとは読めても、すらすらとは読めない小説」, then you would have no choice but to use が there. It cannot be replaced by は in a relative clause/sub clause.