The Rabanan say on 55b that we only give a Karpaf between two cities. According to Chiya bar Rav, we only give a single Karpaf to the two of them. This means that if they are separated by more than 70 Amos, they are not considered a single city as far as Techum is concerned.
According to Rav Chiya bar Rav's reading of the Rabanan, what point were they making by stating that "we give a Karpaf between two cities"? Of course we give a city a single Karpaf - why even if there is a bridge or something within 70 Amos of the city we join it to the city, as our Mishnah states! Why should I have thought that if there is another city within 70 Amos of this one, we do not join it to the first city?
Q. Reese, Atlanta, Georgia
The Ritva on 57a quotes Rabeinu Tam as explaining that the Rabanan hold, as you stated, that the city would be extended even to another house, not specifically a city. Why, then, did they not state a house? He explains that because Rebbi Meir was specifically discussing cities, the Rabanan also stuck to the topic of cities.
Kol Tuv,
Yaakov Montrose