question: What is the common assumption of what Bern was named after ?
answer: a pre-existing toponym of Celtic origin , possibly * berna `` cleft ''
turker_answer: The common assumption of what Bern was named after was a pre-existing toponym of Celtic origin , possibly * berna `` cleft '' .
rule-based: The common assumption of what Bern was named after is a pre-existing toponym of Celtic origin , possibly * berna `` cleft .