**BlockIP**

BlockIP implements a specialized primal-dual long-step path-following in= terior point algorithm for large scale linear, separable convex quadratic, = or separable convex nonlinear problems with primal block-angular structure,= i.e., problems whose variables and constraints can be partitioned in block= s, with some linking constraints coupling all of them. For some huge (milli= ons of variables and/or constraints) quadratic problems have shown to be or= ders of magnitude faster than other approaches. In the electrical energy fi= eld it can be appropriate for any problem that fits the above block-angular= structure (for instance, multi-period or multi-product problems).=E2=80=A8= =E2=80=A8Some references:=E2=80=A8=E2=80=A8J. Castro, Interior-point solver= for convex separable block-angular problems, =E2=80=A8Optimization Methods= & Software, (2016), 31, 88-109.=E2=80=A8=E2=80=A8J. Castro, J. Cuesta,= Quadratic regularizations in an interior-point method for =E2=80=A8primal = block-angular problems, Mathematical Programming, 130 (2011) 415-445.=E2=80= =A8=E2=80=A8J. Castro, A specialized interior-point algorithm for multicomm= odity network =E2=80=A8flows, SIAM Journal on Optimization, 10 (2000), 852-= 877.=E2=80=A8=E2=80=A8Package webpage: http://www-eio= .upc.es/~jcastro/BlockIP.html=E2=80=A8

**SCIP**

SCIP is a framework for Constraint Integer Programming. In particular, i= t can be used as a global solver for general MINLP. It currently implements= an LP-based branch and bound algorithm. SCIP is design in a plug-in fashio= n, which allows to be easily extendible to handle different non-linear cons= traints. As a particularly relevant constraint for some energy problems (ga= s network expansion, water distribution network, etc) is the so-called absp= ower, which models l <=3D abs(x)^p * x - a * z <=3D r, where l,= r,p,a are constants and x,z are variables. This constraint is supported by = SCIP as well as quadratic constraints and many others.

As for references of SCIP:

http://mpc.zib.de/index.php/MPC/article/view/4<= /a>

http://link.springer.com/chapt= er/10.1007%2F978-1-4614-1927-3_15

and Stefan Vigerske's Phd Thesis:

Humboldt-University Berlin, 2013

http://edo= c.hu-berlin.de/dissertationen/vigerske-stefan-2012-08-21/PDF/vigerske.pdf

As for applications of SCIP:

http://www.aimscienc= es.org/journals/displayArticlesnew.jsp?paperID=3D7953

http://bookstore.siam.org/mo21

http://www.tandfonline.com/doi= /abs/10.1080/10556788.2014.888426

**Contributors**:

Prof. Jordi Castro, Universitat Polit=C3=A8cnica de C= atalunya

Dr. Felipe Serrano, ZIB

Dr. Ambros Gleixner, ZIB