Added description

Author: GalinBistrev2

_data/contributors.yml

@@ -29,7 +29,18 @@
  education: "Nuclear and particle physics , Sofia University "St. Kliment  Ohridski , Bulgaria" 
  current: 1
  past_info:
- description:
+ title: "Implementing AD in CMS Combine"
+ description: This project aims to introduce automatic differentiation techniques into the CMS Combine tool. Combine is the primary statistical analysis tool used in CMS and is based on the RooFit software. 
+ Recently RooFit has started using automatic differentiation (AD) technology to aid minimization algorithms.
+ Computationally cheap gradients produced by AD can improve performance of the larger workflows in Combine by more than 5x as demonstrated at ICHEP.
+ The way how RooFit implements AD also benefits the shareability of likelihoods.
+ To get the likelihood gradient, RooFit transforms the likelihood from its internal representation to simple standalone C++ code, which is then used to generate the gradient code. 
+ This can help collaborators without RooFit and Combine expertise to work with likelihoods from Combine at a lower level. 
+ Adopting AD in Combine requires further collaboration between the parties.
+
+ This project aims to bring this AD support into Combine. Aspects include reducing some of the code in Combine in favor of more standard RooFit primitives; 
+ Implementing AD support for Combine-specific RooFit primitives; and writing benchmarks to showcase the benefits of RooFit AD in Combine. 
+ The student selected for this project will work with several high-energy physics codes as well as the LLVM compiler ecosystem.
  mentors: Vasil Vassilev,David Lange,Jonas Rembser