For the ride sharing and chromatic shortest paths, the following papers may
provide some initial pointers. Feel free to search the web for others.



1. Ride Sharing.
	Algorithms for Trip-Vehicle Assignment in Ride-Sharing
		Xiaohui Bei and Shengyu Zhang
	(http://www.ntu.edu.sg/home/xhbei/papers/ridesharing.pdf)



2. Chromatic Paths:

	Improved Approximation Bounds for the Minimum Constraint Removal Problem.
	Sayan Bandyapadhyay, Neeraj Kumar, Subhash Suri and Kasturi Varadarajan.

	(http://drops.dagstuhl.de/opus/volltexte/2018/9406/pdf/LIPIcs-APPROX-RANDOM-2018-2.pdf)


	Approximation algorithms and hardness results for labeled connectivity problems
	Refael Hassin, Jerome Monnot, Danny Segev

	(https://link.springer.com/content/pdf/10.1007%2Fs10878-007-9044-x.pdf)


3. Brain networks

	Analytic tractography: A closed-form solution for estimating local white matter 
		connectivity with diffusion MRI
	https://www.sciencedirect.com/science/article/pii/S1053811917310625


	 A Reeb Graph Approach to Tractography.
	http://www.cs.ucsb.edu/~suri/psdir/Reeb.pdf