という usage in relative clauses


I'm going through this tae kim's guide lesson about some uses of いう:
<http://www.guidetojapanese.org/learn/grammar/define>

And there is something that I don't understand. In the following sentences:

  * 主人公が犯人だったというのが一番面白かった。
  * 日本人はお酒に弱いというのは本当？
  * 独身だというのは、嘘だったの？
  * リブートというのは、パソコンを再起動するということです。

They always use というの. But if I used just の, would it be incorrect? If not,
what is the difference? are という and というの interchangeable? Also, they don't say
anything about ということ in this lesson, so would the same rules apply?




Adjectival clauses are clauses that modify a noun just as adjectives do.
Adjectival clauses in Japanese precede the modified nouns. There are 2 kinds
of adjectival clauses:

  * Relative clauses

  * Noun complement clauses

# Relative clauses

The characteristic of relative clauses is the existence of gaps which are the
modified nouns.

> The girl [whom I met ______ yesterday] is Jane.
>
> 「僕が昨日会った」女性はジェーンです。

# Noun complement clauses

Unlike relative clauses, noun complement clauses have no gaps.

> I got a notification [that my teacher will not come tomorrow] from my
> friend.
>
> 私は、友達から「先生が明日来ない」という知らせを受けた。

Clauses obtained by nominalizing the predicate (in the plain form) with こと and
の can also be regarded as noun complement clauses.

> I know that the teacher will not come.
>
> 先生が来ないのは知っています。

Here, という can be added optionally.

> 先生が来ないというのは知っています。

_Note:_ If you think my answer is either wrong or unclear, feel free to edit
it as many as you want. I have set it to community wiki.

