the High AoA protections did/do not function with a single AoA input, but the stall warning does? I cannot understand the logic.
You'd want stronger evidence to fire an automatic protection than for sounding a warning.
Further, I think it would probably help some readers a lot to read PBL's posts replacing the word "algorithm" with "rule".
For example, if you decided to treat no change as evidence of failure, how would that work in the cruise with a sensor that fails in such a way as to start producing random readings, or to diverge from the facts steadily? Such a rule would be defeated by what might be the most likely non-obvious failure case (a/c in the cruise and therefore maintaining a steady AoA, one or two units fail actively). Obviously there'd be some change, but even a functioning-but-frozen unit would be expected to have a noise term.