A collection of functions for modeling fissile material operations in nuclear facilities,
    based on Zywiec et al (2021) <doi:10.1016/j.ress.2020.107322>.

An R implementation of the Critical Path Method (CPM).
    CPM is a method used to estimate the minimum project duration and determine 
    the amount of scheduling flexibility on the logical network paths within the 
    schedule model. The flexibility is in terms of early start, early finish, 
    late start, late finish, total float and free float. Beside, it permits 
    to quantify the complexity of network diagram through the analysis of 
    topological indicators. Finally, it permits to change the activities duration 
    to perform what-if scenario analysis. The package was built based on following 
    references: To make topological sorting and other graph operation, we use 
    Csardi, G. & Nepusz, T. (2005) 
    <https://www.researchgate.net/publication/221995787_The_Igraph_Software_Package_for_Complex_Network_Research>;
    For schedule concept, the reference was Project Management Institute (2017) 
    <https://www.pmi.org/pmbok-guide-standards/foundational/pmbok>;
    For standards terms, we use Project Management Institute (2017) 
    <https://www.pmi.org/pmbok-guide-standards/lexicon>;
    For algorithms on Critical Path Method development, we use 
    Vanhoucke, M. (2013) <doi:10.1007/978-3-642-40438-2> and 
    Vanhoucke, M. (2014) <doi:10.1007/978-3-319-04331-9>; 
    And, finally, for topological definitions, we use
    Vanhoucke, M. (2009) <doi:10.1007/978-1-4419-1014-1>.

Solving the problem of project management using CPM (Critical Path Method), PERT (Program Evaluation and Review Technique) and LESS (Least Cost Estimating and Scheduling) methods. The package sets the critical path, schedule and Gantt chart. In addition, it allows to draw a graph even with marked critical activities. For more information about project management see: Taha H. A. "Operations Research. An Introduction" (2017, ISBN:978-1-292-16554-7), Rama Murthy P. "Operations Research" (2007, ISBN:978-81-224-2944-2), Yuval Cohen & Arik Sadeh (2006) "A New Approach for Constructing and Generating AOA Networks", Journal of Engineering, Computing and Architecture 1. 1-13,     Konarzewska I., Jewczak M., Kucharski A. (2020, ISBN:978-83-8220-112-3), Miszczyńska D., Miszczyński M. "Wybrane metody badań operacyjnych" (2000, ISBN:83-907712-0-9).