Title An improved upper bound on the independent double Roman domination number of trees Type of Research Article Keywords An improved upper bound on the independent double Roman domination number of trees Abstract An improved upper bound on the independent double Roman domination number of trees Researchers (First Researcher)، Hossein Abdollahzadeh Ahangar (Second Researcher)، Mustapha Chellali (Third Researcher)، Seyed Mahmoud Sheikholeslami Kavkani (Fourth Researcher)