The title "S and es" implies that you're treating "show" and "acts" as nouns. These words, however, are capable of being used both as a noun and as a verb, and in your quote the two words are being used as verbs. You can see the question below (actually very recent!) on another example of this:
Correct word order and subject-verb agreement: "..his associate volunteers..."
And yes, these verbs are conjugated correctly. "Show" is third-person plural, which works with "proposed technique and existing technique" as the subject. Meanwhile, "acts" is third-person singular, which works with "proposed technique" as the subject.
(By the way, rewriting "proposed technique and existing technique" to "proposed and existing techniques" makes the tense a lot clearer.)