Using the command make, the project is compiled using the swipl compiler and a program flp20-log is created.

After the compilation (see the section above), it can be run as follows:

$ ./flp20-log < input-file > output-file

input-file is the name of an input file with a Turing machine and with an initial tape in a specified format. output-file is the name of the output file where a sequence of tapes used during the computation is going to be stored.

The program simulates a given nondeterministic Turing machine. An input specification of the machine and an initial tape are first parsed and their format is validated. In case the format is invalid, an error message is printed to the standard output and the program is terminated. Otherwise, all the given rules are added to the program as dynamic predicates and the simulation with the initial tape is started. Prolog tries to find a sequence of tapes that leads to the final state according to the stored rules. The simulation fails if there is no such sequence that leads to the final state. If the simulation succeeds, the sequence of tapes used during the computation is printed to the standard output.

In the directory tests, there are some testing input files (.in extension) and corresponding outputs (.out extension). There is a description of these files (# denotes the blank symbol):

• invalid-format - invalid format of an input file (there are some illegal characters). Running time: 0.014s.
• abnormal-termination - abnormal termination of a Turing machine (there is no final state). Running time: 0.020s.
• ref - a reference example. Running time: 0.013s.
• ab - accepts the following language (a|b)^n###.... Running time: 0.116s.
• an-bn - modifies the tape from the format #a^n###... to the format #b^n###.... Running time: 3.863s.
• a2n-abn - modifies the tape from the format #a^(2n)###... to the format #(ab)^n###.... Running time: 1.039s.
• anbncn - accepts the following language #a^nb^nc^n###... (the global stack limit likely needs to be increase). Running time: 29.203s.