The program Popeye solves chess problems. It was created by Philippe Schnoebelen in Pascal language and operating system MS-DOS in 1983. Later it was transcripted in C language and was maintained and improved by many programmers, (as Elmar Bartel, Norbert Geissler, Thomas Maeder, Torsten Linss, Stefan Hoening, Stefan Brunzen, Harald Denker, Thomas Bark and Stephen Emmerson).
The program Popeye has got many interfaces in order to be used in other operating systems. I use it through program Fancy (by Marek Kwiatkowski). I open Fancy, place easily the pieces on the chessboard, specigy the kind of problem and the valid conditions and the twin positions, and then Popeye is called. Popeye shows a page with the data from Fancy (I can edit this page) and proceeds to the solution. The solution is written on a text file, which can also be edited.
Some notes here :
(1) The program Fancy (in edition 2.9), besides Popeye 4.51, can call other solving programs, as is Stockfish 1.6.3 JA (for solving studies). The creator of Fancy has declared that edition 2.9 is the last one, so we do not expect any improvements.
(2) The program Popeye accepts many commands (see http://www.strategems.org/beginners/software/Popeye/Popeye.htm). It has happened in composing competitions (as in the World Conference in Crete 2010 with the condition CapZug, see here), to be given instructions for modification of commands, so the program can cope with the new kind of chess compositions.
(3) A way of using Popeye is presented by the new composer Julia Vysotska analytically here.
(4) The software programs Popeye and Fancy can be downloaded from the internet free of charge.