eq { diff { hop { filter_eq { all_rows ; location ; beijing } ; year } ; hop { filter_eq { all_rows ; location ; hiroshima } ; year } } ; -4 } = true
select the rows whose location record fuzzily matches to beijing . take the year record of this row . select the rows whose location record fuzzily matches to hiroshima . take the year record of this row . the second record is 4 larger than the first record .