pandas strictly increasing column group by

Question

dates=[\'2020-12-01\',\'2020-12-03\',\'2020-12-04\', \'2020-12-01\',\'2020-12-03\',\'2020-12-04\']
symbols=[\'ABC\',\'ABC\',\'ABC\',\'DEF\',\'DEF\',\'DEF\']
v=[1,3,5