Does Pregel allow the structure of a graph to be modified?

Does Pregel allow the structure of a graph to be modified?

References

Reference NO 1

http://stackoverflow.com/questions/15205807/does-pregel-allow-the-structure-of-a-graph-to-be-modified

Reference NO 2

https://wiki.engr.illinois.edu/download/attachments/188588798/pregel.pdf?version=1

Reference NO 3

http://googleresearch.blogspot.com/2009/06/large-scale-graph-computing-at-google.html

Reference NO 4

http://www2.hawaii.edu/~lipyeow/ics624/2011spr/pregel.pptx

Reference NO 5

http://www.michaelnielsen.org/ddi/pregel/

Reference NO 6

http://kowshik.github.io/JPregel/pregel_paper.pdf

Reference NO 7

http://cseweb.ucsd.edu/~dlogothetis/docs/clouddb12.pdf

Reference NO 8

http://www.royans.net/arch/pregel-googles-other-data-processing-infrastructure/