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Chapter 2
Syntax and meaning of
Prolog Programs
type
PROLOG
symbol, integer, real, char
domains
variable name = type
predicates
relation(variable name, variable name, …)
goal
run(X).
clauses
relation(value,value,…).
conclusion
:-
condition.
conclusion if condition.
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Chapter 2
TURBO PROLOG
ftp://172.28.80.6/older/DosProgram/TPROLOG
Alt + Enter = Big Screen
F1 : Help
F2 : Save
F3 : Load
F6 : Next/Switch
F8 : Previous Goal
F9 : Compile
F10 : Step (For trace) / End
Alt + T : Trace ON/OFF
Set up  window size  edit Use arrow key to adjust the size
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Chapter 2
PREDEFINED DOMAINS
char 1 byte characters
integer
2 byte integer numbers
real 8 byte floating point
numbers
symbol
strings inserted in the
internal symbol table
string
sequences of chars
"hello world\n"
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Chapter 2
SUMMARY OF PROGRAM SECTIONS
Options must precede the other sections
CONSTANTS
const1 = definition
const2 = definition
[GLOBAL] DOMAINS
dom [,dom] = [reference] declaration1; declaration2
listdom = dom*
dom = <basisdom>
[GLOBAL] DATABASE [ - <databasename> ]
[determ] pred1(....)
pred2(.....)
GLOBAL PREDICATES
[determ|nondeterm] pred1(.........)
-(i,i,o,..)(i,o,i,..) [ language c|pascal|fortran ] [ as "name"
]
pred2(........)
PREDICATES
[determ|nondeterm] pred1(.........)
pred2(........)
CLAUSES
p(....):-p1(...), p2(.....), ... .
p(....):-p1(...), p2(.....), ... .
include "filename"
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Include a file during compilation.
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Chapter 2
MISCELLANEOUS
random(RealVariable)
(real) - (o)
random(MaxValue,RandomInt)
(integer,integer) - (i,o)
sound(Duration,Frequency)
(integer,integer) - (i,i)
beep
date(Year,Month,Day)
(integer,integer,integer) - (o,o,o) (i,i,i)
time(Hours,Minutes,Seconds,Hundredths)
(integer,integer,integer,integer) - (o,o,o,o)
(i,i,i,i)
trace(on/off)
(string) - (i) (o)
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Chapter 2
ERROR & BREAK CONTROL
trap
(PredicateCall,ExitCode,Predicate
ToCallOnError)
exit
exit
(ExitCode)
(integer) - (i)
if exit to DOS then the DOS errorlevel
task processing variable will
contain the value given to the exit
predicate.
break (on/off)
(string) - (i) (o)
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Chapter 2
EDITOR
display(String)
(string) - (i)
edit(InputString,OutputString)
(string,string) - (i,o)
edit(InputString,OutputString,Headstr,Headstr2,Msg,P
os,Helpfilename,
EditMode,Indent,Insert,TextMode,RetPos,RetStatus)
(string,string,string,string,string,integer,string
,integer,integer,integer,integer,integer,integer)
- (i,o,i,i,i,i,i,i,i,i,i,o,o)
If the user saves the text from the editor,
HeadStr2 will be used as the file name.
editmsg(InputString,OutputString,Headstr,Headstr2,Ms
g,Pos,Helpfilename,RetStatus)
(string,string,string,string,string,integer,string
,integer) - (i,o,i,i,i,i,i,o)
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Chapter 2
WINDOW SYSTEM
makewindow(WindowNo,ScrAtt,FrameAtt,Framestr,Row,Col
umn,Height,Width)
(integer,integer,integer,string,integer,integer,in
teger,integer)
shiftwindow(WindowNo)
(integer) - (i) (o)
gotowindow(WindowNo)
(integer) - (i)
resizewindow(StartRow,NoOfRows,StartCol,NoOfCols)
(integer,integer,integer,integer) - (i,i,i,i)
colorsetup(Main_Frame)
(integer) - (i)
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INPUT
readln(StringVariable)
(string) - (o)
readint(IntgVariable)
(integer) - (o)
readreal(RealVariable)
(real) - (o)
readchar(CharVariable)
(char) - (o)
keypressed
unreadchar(CharToBePushedBack)
(Char) - (i)
readterm( Domain, Variable )
(DomainName,Domain) - (i,_)
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Chapter 2
OUTPUT
write( Variable|Constant * )
nl
writef( FormatString, Variable|Constant* )
In the format string the following options are known after a
percentage sign:
%d Normal decimal number. (chars and integers)
%u As an unsigned integer. (chars and integers)
%R As a database reference number. (database reference
numbers)
%X As a long hexadecimal number. (strings, database
reference numb).
%x As a hexadecimal number. (chars and integers).
%s Strings. (symbols and strings).
%c As a char. (chars and integers).
%g Reals in shortest posible format (default for reals)
%e Reals in exponetial notation
%f Reals in fixed notation
%lf Only for C compatibility (fixed reals)
\n - newline
\t - tabulator
\nnn - character with code nnn
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PROLOG_HELP
ARITHMETIC
Arithmetic operators: +, -, *, /, mod, div
Relational operators: >, <, =, >=, <=, <>,
><
Functions: sin, cos, tan, arctan, ln, log,
exp, sqrt, round, trunc, abs
EX: 1 + 2 = 2 + 1, X = 5/2, X = 5 mod 2,
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5 <> 9
Chapter 2
TURBO PROLOG
Use the example from the EXAMPLE directory to try to program.
Start with EX03EX01.PRO
predicates
likes(symbol,symbol)
clauses
likes(ellen, tennis).
FACTS
likes(john, football).
likes(tom, baseball).
likes(eric, swimming).
likes(mark, tennis).
likes(bill, Activity)
if
likes(mark, Activity)
:-
344-302 LP and Prolog
likes(tom, Activity).
likes(ellen, Activity).
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RULES
Chapter 2
bear.pro
?black(X),big(X)
predicates
?brown(X),big(X)
big(symbol)
small(symbol)
?big(X),black(X)
brown(symbol)
black(symbol)
gray(symbol)
dark(symbol)
?black(X),big(X)
No solution
?brown(X),big(X)
X=bear
?big(X),black(X)
No solution
clauses
big(bear).
big(elephant).
small(cat).
brown(bear).
black(cat).
gray(elephant).
dark(Z) :- black(Z).
dark(Z) :- brown(Z).
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Chapter 2
EX04EX02.PRO
domains
brand, color = symbol
age, price = integer
mileage = real
predicates
car(brand, mileage, age, color, price)
clauses
car(chrysler, 130000, 3, red, 12000).
car(ford, 90000, 4, gray, 25000).
car(datsun, 8000, 1, red, 30000).
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Chapter 2
SUM, MULTIPLY : EX04EX01
domains
product, sum = integer
predicates
add_em_up(sum, sum, sum)
multiply_em(product, product, product)
clauses
add_em_up(X, Y, Sum) :- Sum = X + Y.
multiply_em(X, Y, Product) :- Product = X * Y.
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Chapter 2
sister
Z
parent
X
parent
Y
sister
For any X and Y,
X is a sister of Y if
1.
Both X and Y have the same parent, and
2.
X is a female.
sister(X,Y) :- parent(Z,X), parent(Z,Y), female(X).
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Chapter 2
predecessor
A
parent
B
parent
C
parent
D
parent
E
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predecessor
A
predecessor(X,Z) :parent(X,Y1),
parent(Y1,Y2),
parent(Y2,Z).
parent
B
parent
C
predecessor(X,Z) :parent(X,Y1),
parent(Y1,Y2),
parent(Y2,Y3),
parent(Y3,Z).
parent
D
parent
E
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predecessor(X,Z) :parent(X,Y),
parent(Y,Z).
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Chapter 2
Parent1.Pro
predicates
pam
parent(symbol,symbol)
predecessor(symbol,symbol)
bob
clauses
parent(pam,bob).
ann
parent(tom,bob).
parent(bob,ann).
parent(ann,jim).
jim
parent(jim,joe).
parent(joe,john).
joe
parent(john,jack).
parent(tom,liz).
john
jack
predecessor(X,Z) :- parent(X,Z).
predecessor(X,Z) :- parent(X,Y), parent(Y,Z).
predecessor(X,Z) :- parent(X,Y1),parent(Y1,Y2),parent(Y2,Z).
predecessor(X,Z) :- parent(X,Y1),parent(Y1,Y2),parent(Y2,Y3)
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parent(Y3,Z).
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Chapter 2
predecessor
A
For all X and Z,
X is a predecessor of Z if
there is a Y such that
1. X is a parent of Y and
2. Y is a predecessor of Z.
parent
B
parent
C
parent
D
parent
E
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Chapter 2
Parent2.Pro
predicates
parent(symbol,symbol)
predecessor(symbol,symbol)
clauses
parent(pam,bob).
parent(tom,bob).
parent(bob,ann).
parent(ann,jim).
parent(jim,joe).
parent(joe,john).
parent(john,jack).
parent(tom,liz).
predecessor(X,Z) :- parent(X,Z).
predecessor(X,Z) :- parent(X,Y), predecessor(Y,Z).
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Chapter 2
ISA Relationship
Animal kingdom
isa
Plant kingdom
isa
isa
Animal
isa
isa
Dog
Human
Cat
isa
isa
Suwit
plant
isa
Sunee
Mew
344-302 LP and Prolog
Flower
isa
isa
Toop
isa
Rose
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isa
Carnation
Chapter 2
isa1.Pro
predicates
isa(symbol,symbol)
is(symbol,symbol)
clauses
isa(human,animal_kingdom).
isa(plant,plant_kingdon).
isa(flower,plant).
isa(rose,flower).
isa(carnation,flower).
isa(suwit,human).
isa(sunee,human).
isa(dog,animal).
isa(animal,animal_kingdom).
isa(cat,animal).
isa(toop,dog).
isa(mew,cat).
For all X and Z,
X is a predecessor of Z if
there is a Y such that
1. X is a parent of Y and
2. Y is a predecessor of Z.
isa(white,cat).
is(X,Z) :- isa(X,Z).
is(X,Z) :- isa(X,Y), is(Y,Z).
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Chapter 2