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    Common Prolog Predicates
    (semicolon):
  1. ;::infix= ; ::=(1st) or (2nd).
    (comma): , ::infix= ; ::=(1st) and (2nd). :- ::infix=(1st) if (2nd).
  2. ->::infix= If (1st) then (2nd).
  3. <::infix= Less Than - numerical comparison. Evalutaes both sides..
  4. <=::infix= Less Than or Equal - numerical comparison. Evalutaes both sides..
  5. =::infix= True if both terms are the same, or makes them match..
  6. ==::infix= True if two terms X and Y are identical. Does not force unification..
  7. \==::infix= test for inequality of structures. No unification. =:= ::infix= Equal to - numerical comparison. Evaluates both sides. .
  8. =\=::infix= Unequal to - numerical comparison. Evaluates both sides. .
  9. >::infix= Greater Than - numerical comparison. Evaluates both sides..
  10. >=::infix= Greater than of equal - numerical comparison. Evaluates both sides..
  11. is::infix= Expression is evaluated and X becomes the value..
  12. abolish::= remove all clause/definitions of (_) from the data base.
  13. abort::= Probably terminates current query, or clause, or ... ..
  14. ancestors::= (_) instantiated to list of goals called up to this point..
  15. arg::= (3rd) either becomes or is the (1st)th argument in structure (2nd)..
  16. ascii::= (1st) is/becomes an atomic character with ascii code (2nd).
  17. assert::= Adds clause (_) somewhere in knowledge base..
  18. asserta::= Clause(_) is placed at the beginning of the database..
  19. assertz::= Clause(_) is placed at the end of the database..
  20. atom::= True if (_) is a non-numeric atom..
  21. atomic::= True if (_) is an atom or a number..
  22. body::= (2nd) is set to the body of (1st) ((1st)=Head:-(2nd)).
  23. char(n, a, Z)::= Z set to the nth character in atom a..
  24. close(FileName)::= close file, NOT standard input or output..
  25. conc(Var, term)::= Var is/becomes list [term]..
  26. concat(List, Var)::= Var is/becomes atom made up of elements of List..
  27. consult('filename')::= appends correct terms from file.
  28. consult(['filemane',...])::= consults listed files.. define(Atom(Args)) ::= experimental make unique definition of Atom.
  29. define(Atom, Body)::= experimental make unique definition of Atom..
  30. definition(X,Y)::= Y becomes a clause in definition of atom X..
  31. defop(Precedence, Type, Name)::= Define Name to be an operator, see documents..
  32. dump::=?? builtin( notOp, 0, 0, "dump", dump)..
  33. ed functor::= Starts up your EDITOR on the terms defining functor..
  34. ef file::= Lets you edit a file..
  35. eof::=?? builtin( notOp, 0, 0, "eof", p_eof). ??.
  36. file(FileName,ListOfAtoms)::=After consultation ListOfAtoms shows the predicates defined in FileName.
  37. first_clause(Head, Body)::= Find first clause that fits Head, Body.
  38. free(X)::=?? builtin( notOp, 0, 1, "free", p_free). ??.
  39. free_proc(X)::=?? builtin( notOp, 0, 1, "free_proc", p_free_proc). ??.
  40. functor(T, Functor, Arity)::= T becomes Functor of Arity Arguments.
  41. functor(Term,F,A)::= F becomes name and A the arity of Term..
  42. getc(C)::= C is or becomes the next character on the input.. get0(ASCII):-getc(Char), ascii(Char,ASCII). % gets ASCII code of next char
  43. goal(X,Y,Z)::=?? builtin( notOp, 0, 3, "goal", goal). ??.
  44. halt::= end of session, terminates Prolog..
  45. head(Clause, Head)::= sets Head to be the head of the clasue Clause.. help:- print('To exit input: halt!, To read the manual: man!'),... .
  46. integer(X)::= true if X is instantiated to an integer..
  47. length(List,L)::= L instantiated to number elements in List..
  48. listing::= outputs all user defined clauses on current output.. man:-system('man prolog').
  49. match_args(F,I,L)::= partial match of Ith,I+1th, args with elelements of L..
  50. member(Item, List)::= True if Member in List else generates Members in List..
  51. next_clause(X, Y)::= X must be a Clause in the data base, Y is set to the next..
  52. nl::= Outputs a new line character..
  53. nonvar(X)::= tests if X is currently instantiated to a non-variable term..
  54. not P::= Success if P fails , Variables in P can be uninstantiated..
  55. nth(X, N, L)::= true if Nth element of list L is X, Can set X, N, or L..
  56. numbervars(X,Y,Z)::=?? builtin( notOp, 0, 3, "numbervars", number_vars). ??.
  57. nvars(X,Y)::=?? builtin( notOp, 0, 2, "nvars", nvars). ??.
  58. offset(X,Y)::=?? builtin( notOp, 0, 2, "offset", offset). ??.
  59. op(Precedence, Type, [Name, ..Rest])::= declares list of operators..
  60. pp X::= Print out pretty version of definitions of atom X..
  61. prin(Term,...)::= Output Terms (no spaces between, no nl)..
  62. print(Term,...)::= Output Term with nl..
  63. prompt(Old, new)::= Sets the 'read' prompt to 'new', Old set to previous value...
  64. putc(C)::= Outputs ASCII character for C permanently..
  65. quoted(X)::=?? builtin( notOp, 0, 1, "quoted", quoted). ??.
  66. ratom(X)::= Read atom into X, test if next input atom is X..
  67. read(Term)::= Inputs complete, correct and terminated Term..
  68. read_from_this_file::=?? builtin( notOp, 0, 0, "read_from_this_file", read_in). ??. redefine(atom(Value),newatom(NewValue)) ::= replaces first definition of atom..
  69. redefine(Head,Body,NewHead,NewBody)::= replaces definition..
  70. remob(X)::=?? builtin( notOp, 0, 1, "remob", remob). Remove Object? ??.
  71. rename(X,Y)::=?? builtin( notOp, 0, 2, "rename", rename). ??.
  72. retract(Clause)::= remove first matching clause and unify variables..
  73. retract(Head)::= warning and then remove first unifiable clause..
  74. retract(Head, Body)::= remove first matching clause and unify variables..
  75. retract_head(Head)::= remove first matching clause and unify variables..
  76. save FileName::= Saves data base in file FileName (normally in quotes)..
  77. see(File)::= current input becomes File, and if necesary opens it..
  78. seeing(F)::= F becomes/is the current file..
  79. seen::= close current input file..
  80. sh::= escape temporarily to UNIX by spawning an interactive subshell..
  81. show X::= let user see documentatation..
  82. skip(C)::= Inputs data to match C or matches C to next input.
  83. spy predicate::= Start to trace the predicate..
  84. statistics::= outputs current figures on bindings etc..
  85. system(Command)::= Obeys UNIX command, system('cat help')..
  86. tab(N)::= Outputs N blanks (permanently)..
  87. tell(File)::= The current output becomes File (append mode)..
  88. telling(F)::= F is or becomes the name of the current output file..
  89. term(X,Y,Z)::=?? builtin( notOp, 0, 3, "term", pterm). ??.
  90. time::= turns on some kind of timing mechanism..
  91. told::= close output file.. trace [Predicate,Predicate, ..Rest] ::= turn on tracing of a list of predicates..
  92. univ(F,L)::= Makes functor F match elements of list L. F and/or L can be set..
  93. unlink_clause(X)::= Given X is instantiated to a clause then clause is removed..
  94. unspy predicate::= Stop tracing the predicate.. untrace [Predicate,Predicate, ..Rest] ::= turn off tracing of a list..
  95. var(X)::= true if X is an uninstantiated variable or unified with a variable..
  96. write(Term)::= outputs Term with no period or quotes etc..

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