Aaaargh guys!
I try to keep my magical ideas as simple as possible and you two come out speaking about recursive or nested links?!?!?!
You dazers!

Here are my digressions...
First of all, I would avoid applying equations of magic to complex operations like invocation/evocation.
I think to the formulas like a way to give your own magical microcosm a mathematical base.
Physician have always found difficult to give to "objective world" (that is reality) a mathematical base,
but if you go into the "subjective world", the task proves faaaar more elusive.
Peter Carroll gives us some formulas about enchantment/divination (and IMHO they are useful but questionable),
but I dont' think we'll go much further in this direction, mostly due to the fact you cannot give numbers to
the formula's variables but I must limit to a qualitative speculation.
This said, I suppose you can give two interpretations of "magical link":
1) A proper "magical" link, that is something you have affinities with. (following the axiom of the "law of similarity")
Hence the cerimonial usage of icons and symbols of what they are working with.
2) a link that is "physical" rather than magical. This interpretation follows from General Metadynamics, in wich
the link is provided by some kind of
weird exchange of particles. In my opinion this would be a
risky interpretation, for enchantment would have a quite limited scope.
A more chaotic and less mathematical approach suggests you to switch interpretation as you prefer.

In both case I like to think that the magical link refers to your "area of influence".
The area of influence may be "magical" (a druid in nature) or "physical" (reality you come in
contact with, some way or another).
So, I try to answer your questions
1) i will to obtain a copy of song of solomon...
2) it is my will to meet a girl with armpit hair
3) i am surrounded by rare stones
4) im writing a paper on a possible revolution in america. i do a ritual invocation to THOTH. Where is the magic link?
5) im traveling to europe soon and want to create a servitor for good luck and a safe return. is the sigil and or material base the link?
6) i think im being stolen from and need to know for sure before i go accusing people. is the method of sortilage i use the link? if not what does a link in divination consist of?
1) The more you are "near" to a copy of solomon, the best. If you do some magician acquaintances your chances will grow (through interaction with them), hence the need to do everything possible to make the enchantment happen.
2) Same as above. If you go around and meet womens of various kind, probably one of them (or their female friends) will have armpit hair.
3) Very general enchantment. If you live in a city you are ALREADY surrounded by rare stones, according some interpretation of "rare".
4) If you accept that invocated entities are "inside your mind" I'd say you are your magicall link, so L = 1.
5) You are talking about an evocation (a series of enchantments), not a single enchantment: a modelization becomes far more difficult.
6) I think the link is provided by the stolen thing. It would be quit high, for you and the stealer have touched it in a small timeframe.
With such "free" interpretation of the magical link you can also account for an explanation of WHEN enchantment happen: whenever you are making it increase enough.
But in mathematical terms this means making the magical link a "time dependent" entity: mathematical troubles!

I hope I made myself understood.
More on the subject:
http://iota.goetia.net/Articles/links.htmlI also suggest Pope Pete (if he's reading) writing a chapter on the subject in his forthcoming book, for the matter has proven quite insidious many times.