File r37/packages/eds/tableaux.red artifact 2ad2e09933 part of check-in 72f75b2f9c

module tableaux;

% Definition and manipulation of tableaux using tab structure

% Author: David Hartley

Comment. Tableaux are stored internally in a tagged matrix of 1-forms:

	 tab	::= 'tab . matrix of pf

The external format is a matrix:

	 prefix tab	::= prefix matrix of prefix


endcomment;


symbolic procedure !*a2tab u;
   % u:prefix tab -> tab
   % primitive - not much checking
   if not eqcar(u,'mat) then typerr(u,'matrix)
   else mktab foreach r in cdr u collect
           foreach f in r collect xpartitop f;


symbolic procedure !*tab2a u;
   % u:tab -> prefix tab
   'mat . foreach r in cdr u collect
	 foreach f in r collect !*pf2a f;


symbolic procedure mktab u;
   % u:matrix of pf -> mktab:tab
   'tab . u;


symbolic procedure tableaup u;
   % u:any -> tableaup:bool
   eqcar(u,'tab);


put('tableau,'psopfn,'tableaueval);

symbolic procedure tableaueval s;
   % s:{eds} -> prefix tab
   if not edsp(s := reval car s) then typerr(s,'eds)
   else !*tab2a edscall tableau s;


symbolic procedure tableau s;
   % s:eds -> tab
   % very much like characterseds
   % Only non-empty rows are returned, unless whole thing is empty,
   % in which case a 1xN matrix of zeros is returned.
   begin scalar prl,ind;
   if not pfaffian s or not quasilinearp s then
      rerror(eds,000,
	     "Tableau only works for quasilinear Pfaffian systems");
   s := car tmpind closure s;
   prl := prlkrns s; ind := indkrns s;
   s := foreach f in nonpfaffpart eds_sys s join
           if f := linearpart(f,prl) then {f};
   if null s then return mktab {nlist(nil,length ind)};
   return mktab foreach f in s collect
                   foreach i in ind collect negpf xcoeff(f,wedgefax i);
   end;

endmodule;

end;