1+5+6+7           19
1-5+6+7            9
1*5+6+7           18
1/5+6+7           13
1+5-6+7            7
1-5-6+7           -3
1*5-6+7            6
1/5-6+7            1
1+5*6+7           38
1-5*6+7          -22
1*5*6+7           37
1/5*6+7            8
1+5/6+7            9
1-5/6+7            7
1*5/6+7            8
1/5/6+7            7
1+5+6-7            5
1-5+6-7           -5
1*5+6-7            4
1/5+6-7           -1
1+5-6-7           -7
1-5-6-7          -17
1*5-6-7           -8
1/5-6-7          -13
1+5*6-7           24
1-5*6-7          -36
1*5*6-7           23
1/5*6-7           -6
1+5/6-7           -5
1-5/6-7           -7
1*5/6-7           -6
1/5/6-7           -7
1+5+6*7           48
1-5+6*7           38
1*5+6*7           47
1/5+6*7           42
1+5-6*7          -36
1-5-6*7          -46
1*5-6*7          -37
1/5-6*7          -42
1+5*6*7          211
1-5*6*7         -209
1*5*6*7          210
1/5*6*7            8
1+5/6*7            7
1-5/6*7           -5
1*5/6*7            6
1/5/6*7            0
1+5+6/7            7
1-5+6/7           -3
1*5+6/7            6
1/5+6/7            1
1+5-6/7            5
1-5-6/7           -5
1*5-6/7            4
1/5-6/7           -1
1+5*6/7            5
1-5*6/7           -3
1*5*6/7            4
1/5*6/7            0
1+5/6/7            1
1-5/6/7            1
1*5/6/7            0
1/5/6/7            0

     _ 
I = VI  т.е. квадратный корень из 1, но странно извлекать корни из римских чисел, не правда ли? 
II = XI т.е. арабское 11 равно римское 11, т.к. спички могут изображать и арабскую 1

SET Talk Off

* Какие числа допустимо использовать
Create Cursor curNumber (f1 N(1))
INSERT INTO curNumber VALUES (1)
INSERT INTO curNumber VALUES (5)
INSERT INTO curNumber VALUES (6)
INSERT INTO curNumber VALUES (7)

* Все возможные сочетания символов
* Дубли недопустимы
SELECT a1.F1 as V1, a2.F1 as V2, a3.F1 as V3, a4.F1 as V4 ;
INTO CURSOR curValueAll ;
FROM curNumber a1, curNumber a2, curNumber a3, curNumber a4 ;
WHERE a1.F1<>a2.F1 AND a1.F1<>a3.F1 AND a1.F1<>a4.F1 ;
    AND a2.F1<>a3.F1 AND a2.F1<>a4.F1 ;
    AND a3.F1<>a4.F1

* Какие знаки допустимо использовать
Create Cursor curZnak (f1 C(1))
INSERT INTO curZnak VALUES ('+')
INSERT INTO curZnak VALUES ('-')
INSERT INTO curZnak VALUES ('*')
INSERT INTO curZnak VALUES ('/')

* Все возможные сочетания знаков. 
* Дубли возможны
SELECT a1.F1 as Z1, a2.F1 as Z2, a3.F1 as Z3, a4.F1 as Z4 ;
INTO CURSOR curZnakAll ;
FROM curZnak a1, curZnak a2, curZnak a3, curZnak a4

* Позиции, которые могут охватывать скобки
* и которые имеют смысл, 
* например, бессмысленно охватывать одно число или все 4 числа
Create Cursor curScob (f1 N(1), f2 N(1))
INSERT INTO curScob VALUES (0,0)
INSERT INTO curScob VALUES (1,2)
INSERT INTO curScob VALUES (1,3)
INSERT INTO curScob VALUES (2,3)
INSERT INTO curScob VALUES (2,4)
INSERT INTO curScob VALUES (3,4)

* Возможные сочетания скобок
* Имеют смысл только 2 пары скобок, 
* причем недопустимы пересечения скобок
SELECT a1.f1 as S11, a1.f2 as S12, a2.f1 as S21, a2.f2 as S22 ;
INTO CURSOR curScobAll ;
FROM curScob a1, curScob a2 ;
WHERE a1.f1 = 0 OR ;
    a2.f1 = 0 OR ;
    a1.f2 < a2.f1 OR ;
    (a1.f1 <= a2.f1 AND a1.f2 >= a2.f2)

* Все сочетания
SELECT ;
    IIF(a3.S11=1,"("," ")+IIF(a3.S21=1,"("," ") as S11, ;
    IIF(a2.Z1='-',a2.Z1,' ') as Z1, ;
    a1.V1, ;
    IIF(a3.S12=1,")"," ")+IIF(a3.S22=1,")"," ") as S12, ;
    a2.Z2, ;
    IIF(a3.S11=2,"("," ")+IIF(a3.S21=2,"("," ") as S21, ;
    a1.V2, ;
    IIF(a3.S12=2,")"," ")+IIF(a3.S22=2,")"," ") as S22, ;
    a2.Z3, ;
    IIF(a3.S11=3,"("," ")+IIF(a3.S21=3,"("," ") as S31, ;
    a1.V3, ;
    IIF(a3.S12=3,")"," ")+IIF(a3.S22=3,")"," ") as S32, ;
    a2.Z4, ;
    IIF(a3.S11=4,"("," ")+IIF(a3.S21=4,"("," ") as S41, ;
    a1.V4, ;
    IIF(a3.S12=4,")"," ")+IIF(a3.S22=4,")"," ") as S42, ;
    space(20) as Result ;
INTO CURSOR curResult ReadWrite ;
FROM curValueAll a1, curZnakAll a2, curScobAll a3

select curResult
SCAN
    lcFunction = S11+Z1+STR(V1,1)+S12+Z2+S21+STR(V2,1)+S22+Z3+S31+STR(V3,1)+S32+Z4+S41+STR(V4,1)+S42
    REPLACE Result WITH TransForm(&lcFunction)
ENDSCAN

SET Talk ON
SET Filter To Result = '21 '
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