Mayor Joyce Craig and city officials are off to a good start in a new effort to address homelessness and the downtown. The devil will be in the details of a problem that has several causes of varying degrees of difficulty.

Practical approaches come first. An increased police presence downtown, which had been the case in the recent past but had apparently lessened, is being stepped up, the mayor says.

A pilot program to install port-a-potties at Veterans Memorial Park is a good idea but, again, it is going to have to be monitored.

The tougher problem is to properly assess the homeless population and match it with the best programs.

Mental illness and drug and alcohol abuse are two categories; but it is hard to know just how big a problem there is and how many individuals suffer from each.

That’s why it was encouraging to see that Manchester has been chosen by the Harvard Kennedy School for a program where a group of graduate students will attempt to quantify the homeless number and its related costs.

It will be important to identify how many people are homeless because of addiction or mental illness and how many are not really homeless but adept at panhandling.

An all-day opening of the New Horizons shelter is an ambitious proposal that won’t be easy. But now operating under the Families in Transition umbrella, the plan is worth a shot.

The mayor calls the homeless situation a “moral challenge’’ and it is that, at least in part. Solving it will require time, patience, and not a little praying.