function M = bool2fsa_pt(B,alf0)
% converts a boolean expression for a piecewise testable language
% to a DFSA
% the following boolean expressions are legal:
% 1. (w)     with w in \Sigma^*, corresponding to the shuffle ideal of w
% 2. (a + b)   union, where a,b are boolean expressions
% 3. (a ^ b)   intersection, where a,b are boolean expressions
% 4. (a - b)   negation, where a,b are boolean expressions

% as always, @ stands for the empty word

ops = '()+-^~';  % the operators
% now allowing the new "not" operator
B = procshuffnot(B);
alf = ['@' alf0];
B = strrep(B,' ','');
if ~setcontains(union(alf,ops),B)
  error('Unknown characters used in expression');
end





% abusing the power of matlab:
B = ['(' B ')'];
alfstar = setstar(alf0);

STRS = text2cell_adv(B,alf,'');
OPRS = text2cell_adv(B,ops,'');

REG = OPRS{1};

for j=1:length(STRS)
  str = STRS{j};
  R = alfstar;
  if ~strcmp(str,'@')
    for s=str
      R = [R s alfstar];
    end
  end
  REG = [REG R OPRS{j+1}];
end

M = gregexp2dfsa_fast(REG,alf0);

return