Translation:Tá do leabhar níos spéisiúla.
Why is it "spéisiúla" here? I was expecting "spéisiúil" because it's predicative(?)
Comparative forms of adjectives are usually identical to the feminine genitive singular form.
Adjectives have comparative forms in Irish like (some) do in English. Generally, they're pretty regular.
I was reading in Group 3 of Comparatives and superlatives that you have to make the adjective slender if necessary.How do you know how to do this?