polcott wrote:Any competent software engineer...
Any competent civil engineer can design a bridge that doesn't fall down. Yet they do.
You said in the OP
"Will D ever reach its own.."
Ever means just that. In no situation in no time period.
Any competent engineer (of any discipline) understands that there is a big difference between one single case and all cases for all time.
The problem that you are looking at has been proven to be impossible.
Any compentent engineer then understands that they must then do the following to achieve what you want.
1. Invalidate the original proof
2. Provide a new proof that it can fail. This by itself might provide the first.
That is mathematics and not software.