To ask the Scottish Government, further to the answer to question S5O-00175 by Humza Yousaf on 22 September 2016 (Official Report, c. 100), on what date the minister wrote to the ScotRail Alliance to request the improvement plan; whether it will publish a copy of the letter; when the plan was agreed; whether it will publish the plan in full; by what date customers will see improved services, and what the improvements will consist of.