According to Dr. Mastronarde’s Appendix B on page 391, a stem ending in a Χ switches to a ξ in the future and Aorist. It seems that μάχομαι does not follow that rule. Is it just one of those irregular verbs?
Hi Lukas it is not “irregular” it just forms the future (regularly) as a contract verb.
Look at page 149.
"5. Contract Futures. Some verbs, especially those whose stems end in a liquid (λ, ρ) or a nasal (μ, ν), have -ε- inserted between the verb stem and the tense suffix sigma. In this case the ε was not lengthened; (as often happens in the development of Greek forms) the intervocalic sigma dropped out, and (in Attic) the remaining vowels suffered contraction. The resulting endings are the same as those of the present of verbs in -έω.
Present -------> stem + -ε- + -σ- -------------->future stem
μάχομαι -------> μαχ- + -ε- + (-σ-)-------------->μαχε-"
So a χ does not end the stem of μάχομαι like I thought it did?
Well yes it does, but in the future and aorist there’s what’s known as an infix, an -ε- inserted between the verb stem (μαχ-) and the sigma tense-marker. Why doesn’t it go directly to μαχσ-=μαξ?, you may ask. To which I’d reply, Well, that’s just the way it is. (Actually, of course, there’s more to it than that, but that needn’t concern us.) The important thing is that you recognize the morphological evolution:
μαχέσομαι > μαχέομαι > μαχοῦμαι
So the future ends up looking like the present middle of an -έω contract verb, e.g. ποιέομαι > ποιοῦμαι.
seneca may want to add more.
Εὐχαριστῶ!