Questions & Answers about Nei, reglan er ströng. Þú mátt ekki reykja.
Where does the form mátt come from?
It is the "you" (singular) form of the verb mega (to be allowed to). This verb is irregular in the present tense: ég má (I may), þú mátt (you may), and hann/hún/það má (he/she/it may).
Why is there no að (to) before reykja?
Because mátt is a modal verb. Just like in English ("you may not smoke" instead of "you may not to smoke"), Icelandic modal verbs are followed directly by the bare infinitive of the action verb. Therefore, we drop the að and just write reykja.
Why is the adjective ströng instead of the dictionary form strangur?
Adjectives in Icelandic must match the gender of the noun they describe. The word for rule, regla (here as reglan), is a feminine noun. Therefore, the adjective changes to its feminine singular form, ströng. The vowel shift from 'a' to 'ö' is a very common pattern when making words feminine.
What is the rule for placing ekki (not) in a sentence with two verbs like this?
In a standard main clause, the negative word ekki usually goes immediately after the conjugated verb. Since mátt is the conjugated verb here, ekki steps in right after it, separating mátt from the infinitive reykja.