The Philippine Senate has made it mathematically easier to convict Vice-President Sara Duterte-Carpio, but observers said the ruling could intensify a battle over an impeachment trial already viewed by the public as deeply divisive.The Senate, sitting as an impeachment court, ruled on Wednesday that only senator-judges who are able to take part in the trial should be counted in determining the threshold for conviction.Under the Philippine constitution, a two-thirds vote of the Senate is...