S= I + (S-I) The Object Oriented View

Savings equal Investment plus (Savings minus Investment)

Why did it take me so long to get it?  Because that is not the way I would look at it.  Meaning look at the same thing in a different way.  I got it but when I wrestled it around to my way of looking at it I got it even better.  So now, I could go back and talk to anyone that looked at the same thing from the viewpoint of the original formula.

Savings equal Investment plus (Savings minus Investment)

    Is the same as saying;

Savings equals Investment plus the difference between Savings and everything else called a subset type of of Savings but is not called the subset of Savings identified as Investment Savings.

Or from the object oriented point of view:

Savings equal the total of all subset categories of savings.

Savings is a parent class.  Investment is a child class of Savings.  There are other child classes of savings.  Child classes inherit properties of the parent class.  Keep in mind there may be child classes of child classes but they all have properties of all parent classes above them plus some specific properties that distinguish them as a child of the parent that does not have those properties

Confused?  It is OK.  The point of view shoe is on my foot now.  This is how I look at it.  Roll it around in your head to see it my way like I had to do to see it the original way.  You are on my turf now, no wonder it might at first be hard to see but if you think about it and go to the links contained in the previous paragraph it will become clear.  It is looking at
S= I + (S-I) in a different way.  In a way that may more productive because the examination of S= I + (S-I) can be conducted not with words expressing the thoughts about the basic concept of  S= I + (S-I) in written blog entries but a structured object model expressing the same thing.  Actually, a structured model which is always a step behind the discussion of blog entries as it takes the concensus of the blog entries and reformats it in Object Oriented terms.

Think of it this way:  It is the railroad tracks immediately following the workers that clear the land, make the roadbed, lay the ties and rails.  It shows the way they have come and points to where they are going.  That is a linear relationship example.  Object Oriented is relational.  Still, not a bad example.

Investment has some of the properties of Saving as a child of Savings.  It also has some properties of other parent classes.  Maybe.

While this link discusses inheritance in Object Oriented Programming Languages, The prior work done by analysts to produce a statement and description of relationships that programmers can code used the same method to discover the class structure, how the classes relate to each other and what the properties of all the classes are.  That is called Object Oriented Analysis and Design.  It creates high level abstract model describing the problem domain and then builds it out in increasing detail.  That is how complexity of systems is reduced to simplicity to the extent that everything fits together and can be examined in detail.

So:  Investment is a child of Savings.  It is also a child of a parent or parent that is not savings but through investment has some kind of relationship to savings.  That relationship can be revealed by common links the child has to different parents.  In a system, everything is connected to everything.  Things at any level can be examined individually but the nature of their existence and functional methods has to be looked at systemically.

Savings and Investment are merely one point of entry to the entire system.  Any point of entry could be selected.  There is a problem when the problem domain with a system name becomes two problem domains, two different systems and are analyzed by different analysts as if they were the same system.  At some higher level it is the same system derived from a the common super class. 

Money is a Super Class.  Savings and Investment are somewhere down in the class structure of what money is and does.  It seems that there needs to be much more work done on establishing the properties of the Super Class money before getting into Savings and investment.

MMT addressed the Super Class.  Did it well.  It expresses solid concepts of Super Class: Money.  As it examines and produces analysis of the progression of child classes it begins to express more detailed relationships.  Some analyst designers of MMT got down to level of detail where its examination and expression of the nature of the properties and relationships of a child object conflicted with the nature and properties of as viewed by other MMT analysts and designers. 

Since the analysts were, in effect, inheritor children objects  of the parents of MMT they were at odds with parent MMT thought on some lower level design matters.  They called themselves MMR.

It does not look like MMR intends to define an alternate superclass of money but differences at a subset child level.

MMT would benefit from Object Oriented Analysis and Design Groupware Development Methodologies.