Asked the Minchas Chinuch and Chasam Sofer:
How could we accept the testimony of the witnesses that a city is an עיר נדחת? Not only are the men who served idols killed but according to the Rambam the children are killed as well.
Now, the gemara says that we can't give the punishment to the children of the עדים זוממין because of the drasha לו ולא לזרעו. It emerges that it is impossible to make the witnesses עדים זוממין and thus their testimony is עדות שאי אתה יכול להזימה and not acceptable in court.
So how do we have an עיר נדחת??
Many terutzim have been offered. Can you think of one or two on your own??