Artificial intelligence -> Prolog Language

6. Variables in Prolog get their values by being unified with values. Until it gets a value, a variable is said to be free ; when it gets a value, it becomes bound . When backtracking; variables becomes free again. Variables are used as part of the pattern-matching, process, not as a kind of information storage.

12. domains mydom = i(integer); s(string) predicates procedure wr(mydom) - (i) clauses wr(i(Int)):- write("Was integer: ",Int). wr(s(Str)) :- write("Was String: ",Str). GOAL wr(i(88)). Passing input to the predicate The variable will be bound to 88 Procedure means no fail! Only input flow accepted! Case/switch statement!

14. Erroneous - Always exit failure - Always fail procedure - Always success determ - succeed or fails multi - 1 or more solutions (never fail) nondeterm - 0 or more solutions predicates append(list,list,list)- procedure (i,i,o), determ (i,i,i) nondeterm (o,i,i)

15. write(Param1, Param2, Param3, ..., ParamN) readln(Line) readchar(CharParam) file_str(Filename, Text) - file_str("t.dat", My_text) openread(SymbolicFileName, OSFileName) openwrite(SymbolicFileName, OSFileName) closefile(SymbolicFileName)

17. Stack: the stack is used for transferring arguments and return addresses for predicate calls. The stack also holds the information for backtrackpoints. Heap: the heap holds all objects that are more or less permanent, such as database facts, window buffers, file buffers etc. Gstack: the global stack, normally called gstack, is the place where lists, compound structures and strings are placed. The Gstack is only released during backtracking. Trail: the trail is only used when the program uses reference variables. It holds information about which reference variables must be unbound during backtracking. The trail is allocated in the heap.