Synge's "World Function": History & Significance

[facenian]

Hello, there is already a thread about this but is closed and I'd like to know more. Synge's book was written in 1960 and its mathematical language is a bit old, he presents the concept of world function as a new method. I would like to know if this concept found its way into the literature or it's a Synge's oddity

 

[Demystifier]

It's still in use. See e.g.
http://lanl.arxiv.org/abs/1102.0529
Sec. 3.

 

[robphy]

Possibly useful:
http://www.phy.olemiss.edu/~luca/Topics/w/world_function.html

 

[facenian]

Well, it seems it is alive and kicking so it is worth learning. Thanks