-MİŞ  Past Participle

The participle formed by this suffix refers to actions that occured before the action expressed by the main verb.

It is identical with the reported past suffixö and its variants are ;

-mış 

-miş

-muş

-müş

- Çok iyi pişmiş bir tavuk yedik. 

We ate a very well cooked chicken.

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* This participle is often used with olan, especially if the noun qualified by the participle is human.

- Biletlerini almış olanlar kapıda beklemedi.

Those who had bought their tickets did not wait at the door.

- İstanbul´a daha önce gelmiş olan turistler değişik şeyler görmek istiyor. 

Tourists who have been to Istanbul previously want to see different things.

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In the newspapers you may often see the past participle -MIŞ followed by bulunan, which is almost the same as olan ;

Dün Ankara´ya gelmiş bulunan başbakan bugün mecliste bir konuşma yaptı.

The Prime Minister, who came to Ankara yesterday, made a speech in parliament today.

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* Note that the nouns formed with this participle suffix ;

dolmuş  ---> a shared minibus

geçmiş  ----> the past

Thanks for this. We come accross the structure many times but not so often see it explained.