Simple setup. Have 1 type, which we will call Type with a 1 to many relationships with Type. (Use case is creating tasks that relate to other tasks).

If Type has a formula integer property called Effort, and a parent has a formula integer property that would like to Sum, Max, or Min the properties of Effort on all related child Types

The actual formula for the formula property would look like this in the parent Type

Types.Sum(Effort)

However, that is not possible. The formula editor will not let you use the name Effort.

To get around this, we have to create a proxy formula property. In this case, we will call it EffortProxy.

The formula for this property is just:

Effort

Now in our parent we can use the formula for Effort:

Types.Sum(EffortProxy)

I think what is going on here is that the Formula editor does not let you use the same name property in itself, however, we are not the property of the children, not itself.