I am learning about comparative and superlative of adjectives, but it is so complex. Maybe my textbook tells it too simple.
I wonder that:
(1) For adjectives of the first and second declension(-ος, -η/α, -ον),take δίκαιος for an example. Its comparative is δικαιό-τερος, δικαιο-τέρα, δικαιό-τερον, and I wonder where the ο in the “δικαιό” comes from. As a connective vowel, or considering that the suffix is -ς rather than -ος?
(2) I met a word ἄξιος, whose comparative is ἀξιώτερος, why ω rather than ο?(and superlative of φοβερός is φοβερώτατος)
(3) For adjectives of the third declension(in fact I haven’t learnt that), according to nominative, or genitive?
(maybe you think that they should be included in the textbook, but I use a Chinese one rather than English, and its quality is not so good.)
The -ο- in the words on -ος is a penult (see Wikipedia), in german this vowel is called a „Kennlaut“ („identification-sound“, „marker“ ???): This vowel is added to a root and marks the word as a noun.
So the construction is root - „Kennlaut“ (here: -ο-) -ENDING/SUFFIX.
I have another question after reading the book: do you know the comparatives of κενός and στενός?
The book said that originally they are κενϝός and στενϝός so -ο shouldn’t be lengthened. but wikipedia lengthens them. I suspect that wiki is wrong(there are no pages about their comparatives), but I cannot find enough evidence.