Learn Finnish: Ilman dataa algoritmi ei voi räätälöityä. - Without data, the algorithm cannot become tailored.

The verb is derived from the noun räätäli (a tailor). By adding the automative suffix -öityä, it forms an intransitive verb meaning to become tailored or to adapt itself. The suffix indicates a process that the subject undergoes independently.

What is the difference between using räätälöityä and the standard verb räätälöidä here?

Räätälöidä is a transitive verb meaning to tailor something. If you used it here (algoritmi ei voi räätälöidä), it would mean the algorithm cannot tailor something else. Using the automative räätälöityä shows that the algorithm is the one being customized through an internal or automatic process.

Why is the word dataa in the partitive case?

The word ilman (without) is acting as a preposition in this sentence. When used as a preposition, ilman always requires the word that follows it to be in the partitive case. For the loanword data, we simply add the partitive ending -a to get dataa.

Why is räätälöityä in its dictionary form instead of being conjugated?

It follows the negative auxiliary structure ei voi (cannot). The verb voida (to be able to) always requires the main verb of the sentence to be in the first infinitive, which is the dictionary form.