License

The Population License is similar to the MIT license in adding this clause: for any writing public or private that has resulted from the use of the software population, the reference of this book “Population library, 2012, Vincent Tariel” shall be included in it.

So, the terms of the Population License are:

Copyright © 2012, Tariel Vincent

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software and for any writing public or private that has resulted from the use of the software population, the reference of this book “Population library, 2012, Vincent Tariel” shall be included in it..

The Software is provided “as is”, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the Software.

As linked version, Population software includes some external libraries with compatible licenses:
CIMG,  used for the CImgDisplay facility, LGPL license, so you cannot modify the source code of file CIMG.h for a non open-source utilization,
LOKI, used for generic programming patterns, MIT License,
MTRAND, used to generate random numbers, BSD license,
FunctionParser, used to parse a function, LGPL license, so you cannot modify the source code of file fparser.hh, fpconfig.hh, fptypes.hh and fparser.cpp for a non open-source utilization,
OpenGL, used to 3D computer graphics, Free Software License B,
pugixml, used to read/write/modify XML document, MIT License.