[kayson]

That's harder than you might think. How would you test for all possible uses? Even if you looked at something fundamental like an N-port, you'd still have to define metrics for usefulness and many of the topologies in the paper would evade most obvious circuit metrics.

[amelius]

Well, you are right to some extent, but in practice you don't need "all possible uses" and instead you are looking for a specific behavior, which you can easily encode in a test that uses a simulator.

[ajnin]

The article mentions that circuit 23 was found using an "exhaustive search", so presumably using an automated means.

But I don't think that works in the general case to find all "useful" circuits. For example figure 27 is a pA source and requires 2 precise control voltages and a clock source. 39 is a peak detector. Does not seem that easily encoded.