Limitations of に for emphasis?


I remember having learning that に can be used for a simple emphasis of the
word before it, like so:

> 私はケーキを食べた - I ate cake
>
> 私にはケーキを食べた - _**I**_ ate cake (the others may or may not have, but I did)

But then I stumbled upon something about the に for emphasis not being able to
be used in with verbs that normally can't take it? Does this mean the
following sentences are incorrect, since 知る can't be used with に?

> 私にはその小説を知っている
>
> 誰にも試合の結果を知らない

Or have I completely misunderstood?




I do not know where you learned that に can be used for emphasis, but I do not
know any case where に is used for emphasis. [に is a case
particle](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%81%AB&dtype=0&dname=0na&stype=1&pagenum=1&index=13940200),
and you cannot add に to something that plays roles other than the に-case. (The
に-case is used for many purposes such as time, location, destination,
direction, and purpose).

The following sentences are not grammatical.

  * 私にはケーキを食べた。
  * 私にはその小説を知っている。
  * 誰にも試合の結果を知らない。

Removing に from these sentences makes them grammatical.

  * 私はケーキを食べた。 I ate a cake.
  * 私はその小説を知っている。 I know the novel.
  * 誰も試合の結果を知らない。 No one knows the result of the match.




I do not know where you learned that に can be used for emphasis, but I do not
know any case where に is used for emphasis. [に is a case
particle](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%81%AB&dtype=0&dname=0na&stype=1&pagenum=1&index=13940200),
and you cannot add に to something that plays roles other than the に-case. (The
に-case is used for many purposes such as time, location, destination,
direction, and purpose).

The following sentences are not grammatical.

  * 私にはケーキを食べた。
  * 私にはその小説を知っている。
  * 誰にも試合の結果を知らない。

Removing に from these sentences makes them grammatical.

  * 私はケーキを食べた。 I ate a cake.
  * 私はその小説を知っている。 I know the novel.
  * 誰も試合の結果を知らない。 No one knows the result of the match.

