Lamport acknowledges the report, not the error. I'm still not convinced there even is an error. The state after step 9 should be the same as after step 7, i.e.

Lamport acknowledges the report, not the error. I'm still not convinced there even is an error. The state after step 9 should be the same as after step 7, i.e. `A(-:-,100) B(100:b,100) C(100:b,-)` because C needs to retain the "highest-numbered proposal" it accepted, not the one it accepted last. That means the nine steps outlined in the post/on StackOverflow do not, by themselves, demonstrate any problem. So what additional steps are missing/what alternative steps actually produce an inconsistency/divergence?