On 23 January 2018 at 22:54, Costello, Roger L. <costello@m...> wrote:

Hi Folks,

I am dealing with XML trees.

No id/idrefs. No mixed content.

Just plain old properly nested elements.

Suppose I have a pile of elements and I want a machine to assemble them into a tree of properly nested elements. The machine doesn't know the rules for assembly so I must tell it the constraints on the elements; in particular, the constraints on how they may be nested.

Here's the list of constraints that I've come up with thus far:

1. An element cannot be a descendent of itself, i.e., no loops in the tree.

2. If elements e and e' are children of element E, then e cannot be a child of e' or vice versa.

What other constraints are there?

/Roger

_

  \c

then the 6 permutations of a,b,c so 12 possibilities

But any specification which tells your machine which of the 12 possibilities to build probably doesn't need to check the constraints if it just arranges to always build a tree,.