How to separate words in a Japanese sentence?


Unlike some languages (English, French, ...), written Japanese sentences don't
have spaces between words.

I know that it is the same in Chinese for example, but the fact that the
Chinese language only use one alphabet (hanzi) makes it easier to split words,
most of the time it is 1 or 2 characters for each word.

I also know that a lot of it comes from knowing vocabulary/grammar to be able
to know where each word begins and ends, but I was wondering if there were any
tips that can be used to be able to differentiate them?




Certainly vocabulary helps, but you can get quite far by considering the
structure of a sentence.

  * Nouns are usually written in kanji (or katakana) and are _practically always_ followed by a particle (を, が, は, から, etc.) (unless they are followed by a copula で, だ, です, etc.)
  * The stem of verbs (including adjectival verbs, or "i-adjectives") is usually written in 漢字, with the ending (the conjugated part) written in kana (called 送り仮名).
  * Adverbs are often written in kana
  * Adjectival nouns (AN) ("na-adjectives") are usually written in kanji and usually followed by な.

With that information, you can usually parse a sentence without knowing any
vocabulary (but you need to know a list of particles and knowing the possible
conjugation for verbs also helps).

For example,

> 住宅地域における本機の使用は有害な電波妨害を引き起こすことがあり、その場合ユーザーは自己負担で電波妨害の問題を解決しなければなりません。

becomes

> (N) 住宅地域  
>  (P) に  
>  (V) おける  
>  (N) 本機  
>  (P) の  
>  (N) 使用  
>  (P) は  
>  (AN) 有害な  
>  (N) 電波妨害  
>  (P) を  
>  (V) 引き起こす  
>  **(N)** こと  
>  (P) が  
>  (V) あり、  
>  **(D)** その  
>  **(N)** 場合  
>  (N) ユーザー  
>  (P) は  
>  (N) 自己負担  
>  (P) で  
>  (N) 電波妨害  
>  (P) の  
>  (N) 問題  
>  (P) を  
>  (N) 解決  
>  (V) しなければなりません。

where for the bold lines, I needed to know that

  * こと is a nominalizer, i.e. some sort of auxiliary noun, and thus is not written in 漢字
  * その is a determiner and not an adverb
  * 場合 is also an auxiliary noun and doesn't take a particle here.

But as you can see, you get quite far with the handful of rules above.




Certainly vocabulary helps, but you can get quite far by considering the
structure of a sentence.

  * Nouns are usually written in kanji (or katakana) and are _practically always_ followed by a particle (を, が, は, から, etc.) (unless they are followed by a copula で, だ, です, etc.)
  * The stem of verbs (including adjectival verbs, or "i-adjectives") is usually written in 漢字, with the ending (the conjugated part) written in kana (called 送り仮名).
  * Adverbs are often written in kana
  * Adjectival nouns (AN) ("na-adjectives") are usually written in kanji and usually followed by な.

With that information, you can usually parse a sentence without knowing any
vocabulary (but you need to know a list of particles and knowing the possible
conjugation for verbs also helps).

For example,

> 住宅地域における本機の使用は有害な電波妨害を引き起こすことがあり、その場合ユーザーは自己負担で電波妨害の問題を解決しなければなりません。

becomes

> (N) 住宅地域  
>  (P) に  
>  (V) おける  
>  (N) 本機  
>  (P) の  
>  (N) 使用  
>  (P) は  
>  (AN) 有害な  
>  (N) 電波妨害  
>  (P) を  
>  (V) 引き起こす  
>  **(N)** こと  
>  (P) が  
>  (V) あり、  
>  **(D)** その  
>  **(N)** 場合  
>  (N) ユーザー  
>  (P) は  
>  (N) 自己負担  
>  (P) で  
>  (N) 電波妨害  
>  (P) の  
>  (N) 問題  
>  (P) を  
>  (N) 解決  
>  (V) しなければなりません。

where for the bold lines, I needed to know that

  * こと is a nominalizer, i.e. some sort of auxiliary noun, and thus is not written in 漢字
  * その is a determiner and not an adverb
  * 場合 is also an auxiliary noun and doesn't take a particle here.

But as you can see, you get quite far with the handful of rules above.

