1:- module(math, [boole/2,
    2		 pairs/2,
    3		 choices/2,  product/3,
    4		 powerlist/3, powerset/2,
    5		 string_to_ground_term/2,
    6		 subst/3,
    7		 nCr/3, combi/3, combination/4,
    8		 fun_to_rel/2, rel_to_fun/2,  principal_filter/3,
    9		 all_maps/3,
   10		 filter/3, inverse_image/3, image/3,
   11		 bigcap/2,
   12		 raise_list/3, distribute_cons/3,
   13		 fact/2, factorial/2, factorial/3,
   14		 permutations/2
   15		 ]).   16:- use_module(pac(basic)).   17:- use_module(util(meta2)).   18:- use_module(pac('expand-pac')).   19
   20term_expansion --> pac:expand_pac.
   21
   22:- use_module(pac(op)).   23:- use_module(zdd('zdd-array')).   24
   25
   26% ?- factorial(54, X).
   27% ?- X is (10000)^2.		%億
   28% ?- X is (10000)^3.		%兆
   29% ?- X is (10000)^4.		%京
   30% ?- X is (10000)^5.		%
   31% ?- X is (10000)^6.
   32% ?- X is (10)^68.			% 無量大数
   33
   34% ?- X is (10)^68.			% 無量大数
   35% ?- factorial(54, F), X is 10^68, R is rdiv(F, X).
   36%@ F = 230843697339241380472092742683027581083278564571807941132288000000000000,
   37%@ X = 100000000000000000000000000000000000000000000000000000000000000000000,
   38%@ R = 839804478670853788470022637495376624731865611727r363797880709171295166015625000000000000000000 .
   39
   40% ?- factorial(54, F), X is 10^68, Q is F//X.
   41%@ F = 230843697339241380472092742683027581083278564571807941132288000000000000,
   42%@ X = 100000000000000000000000000000000000000000000000000000000000000000000,
   43%@ Q = 2308 .
   44
   45% ?- list_to_brace([[]], X).
   46% ?- list_to_brace([[],[]], X).
   47% ?- list_to_brace([[],[], []], X).
   48
   49:- bekind(list_to_brace, []).
   50[] = `({}).
   51[X] = `({})@X.
   52[X|Y] = `({})@ (`(',')@X@Y).
   53:- ekind.   54
   55% ?- str("ab" + "cd" + "ef", X).
   56%@ X = "abcdef".
   57% ?- eval(str::("ab" + "cd" + "ef"), X).
   58%@ X = "abcdef".
   59
   60:- bekind(str, []).   61X+Y =  :string_concat@X@Y.
   62% X+Y =  :pred([X, Y, Z]:- string_concat(X, Y, Z))@X@Y.  %% OK
   63X