-- file B_tree_for_bigs_wdix.stl
package B_tree_for_wdix;		-- B-trees, realized as objects
-- ***************************************************************************************************************
-- ****** B-tree variant for word index, with 2 cumulants (no. of occs, last wd. in parent), refcounts  ******
-- ***************************************************************************************************************
	-- Refcounts can be ignored except in the wix_set_comp, wix_insert, split_node, share_right, join_left,
	-- and join_left routines.
-- This B-tree represents the words-to-number-of-occurences index 

-- Given an indexable word associated with a database, this tree indexes to the start, in the word-occurences
-- bigstring, of the corresponding occurences list. It stores (as cumuants) the cumulated length
-- of all such occurences lists, and the first 10 or 11 characters of each indexed word. 
-- To deal with indexed words larger than this, we use a special 'self-defining' encoding, keep the first part
-- of each excessivley long word in the tree, and store the remainder of the word (which can be of any
-- length up to 32K characters) ast the start of the corresponding occurences section.
-- (For compatibility with existing code, a zone whose length is a multiple of 4 bytes is used for this.)
-- The self-defining encoding used is as follows. Words of up to 128 bytes are padded with zero bytes
-- to at least 11 bytes (but if longer than 11 bytes, always to one less than a multiple of 4 bytes),
-- and are preceded by an extra byte giving the string length. Words of more than 128 bytes 
-- (but of no more than 32K bytes) are preceded by two bytes giving their string length (the first byte being 
-- incremented by 128 to distinguish it from the preceding case), and padded with zero bytes to 2 less than
-- a multiple of 4 bytes.

-- This index stores words in the alphabetical order of these encoded forms. So to search for a word W
-- of up to 11 bytes, we use its encoded form to search as usual; when the first larger word FLW
-- has been found we know immediately from the first 12 bytes of FLW whether it equals W. We search
-- for words of more than 11 words in the same way. However, when the first potentially larger word is found
-- (examining the lead 12 bytes only) we may have to examine its additional bytes (stored at the start
-- of the corresponding occurences section) to determine whether this is indeed larger, and if
-- not my need to conduct a binary search among words with the same 12 lead bytes to find the first largest.
-- However, such coincidences of word length and first 10 actual bytes should be infrequent. 
-- Obviously the treatment of such longer words is substantially less efficient than that of words of up to
-- 11 bytes in length. To avoid searches on longer words, the database fructions that transform of records
-- into lists of words should be designed to compress words where possible, e.g. by compressing integers, 
-- and by using auxiliary encoding dictionaries to replace words by word numbers. 

const wix_code_pts := {"wix_last1", "wix_last2", "wix_nlast2", "wix_nlast1", "wix_nc1", "wix_nc2",
	"wix_set_copy", "wix_last1", "wix_last2", "wix_nc1",
	"wix_comp1", "wix_ndel_nc", "wix_ndel_comp",
	"wix_ndel_comp_last", "wix_ndel_comp_nlast", "wix_del_nc", "wix_del_nc_have",
	"wix_del_comp", "wix_del_comp_last", "wix_del_comp_nlast", "wix_del_comp_enough",
	"wix_del_comp_canpull", "wix_del_comp_canjoin", "wix_del_comp_npop", "wix_del_pop",
	"wix_in_copy", "wix_in_nend2", "wix_in_nend1", "wix_in_nend3", "wix_in_end",
	"wix_in_end_nc", "wix_in_end_nc_nos", "wix_in_end_nc_split", "wix_in_end_comp",
	"wix_in_end_comp_nos", "wix_in_end_comp_split", "wix_in_end_comp_nosthis",
	"wix_in_end_comp_splitthis", "wix_in_nend_nc", "wix_in_nend_nc_nos",
	"wix_in_nend_nc_split", "wix_in_nend_comp", "wix_in_nend_comp_nos",
	"wix_in_nend_comp_split", "wix_in_nend_comp_nosthis",
	"wix_in_nend_comp_splitthis", "wix_halves_nc", "wix_halves_comp",
	"wix_pull_left", "wix_pull_right", "wix_share_nc", "wix_share_comp",
	"wix_share_copy", "wix_share_copy2", "wix_share_move_left", "wix_share_move_right",
	"wix_join_left_comp", "wix_join_left_nc", "wix_join_left_copy", "wix_join_right_comp",
	"wix_join_right_nc", "wix_join_right_copy"};			-- code points to be traversed

var debug_val := 0;
var prior_debug_c := 0,debug_c := 0;		-- global variables for debugging

var tree_level;					-- tree level for recursive insertion process
	
procedure wix_comp(rec,j);			-- fetch of component containing cumulant j
procedure wix_comp2(rec,j);			-- fetch of component containing second cumulant j
procedure wix_comp_cum(rec,x);		-- fetch of component containing cumulant x, with cumulants
procedure wix_comp_cum2(rec,x);		-- fetch of component containing second cumulant x, with cumulants
procedure wix_set_comp(rw rec,w,x);	-- assignment of the first component whose cumulant is at least w; w must be in range
procedure wix_set_comp2(rw rec,w,x);	-- assignment of the first component whose second cumulant is at least w
procedure wix_insert(rw rec,j,x);		-- insertion before j-th component; or at the end if j = OM
procedure wix_insert2(rw rec,j,x);	-- insertion before component with second cumulant at least j; or at end (j = OM)
procedure wix_get_cum(rec);			-- get the cum value (string length) for this node
procedure wix_get_cum2(rec);			-- get the record id string cum value of the final child of this node

procedure encode_wd(wd);		-- puts word into length-prefixed, self-defining form described above
procedure decode_wd(stg);		-- recovers word from length-prefixed, self-defining form described above

procedure wix_make_from_tuple(t);		-- make B-tree representation from tuple (DEBUGGING ONLY)
procedure wix_dump(rec);			-- get tuple from B-tree representation (DEBUGGING ONLY)
procedure num_leaves(a_tree); 		--  (DEBUGGING ONLY)
procedure wix_check_tree_structure(tree);		-- recursive check of tree structure (DEBUGGING ONLY)

end B_tree_for_wdix;

package body B_tree_for_wdix;		-- B-trees, realized as objects
use setldb,byteutil,disk_records_pak,db_records,string_utility_pak;

const zeroes11 := "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
const zeroes4 := "\x00\x00\x00\x00";

				-- there are two cumulants, the total length of the records and the recid 

procedure xwix_create();						-- creation routine

	rec := dr_new_rec();			-- create a new record (at this point, the record is loaded
								-- dirty, and holds all zeroes; so it is not compound)
	set_type(rec,wd_index_node_ncr);	-- set to non-compound tree
	return rec;
	 
end xwix_create;

procedure wix_get_cum(rec);		-- get the integer cum value of the final child of this node
if int_of_4(rec) = 0 then print("bad rec in wix_get_cum: ",debug_val); stop; end if;
	if (nc := num_childr(rec)) = 0 then return 0; end if;
	return get_ch_cum(rec,nc);
	
end wix_get_cum;

procedure get_ch_cum(rec,j);	-- get the integer cum value for the j-th child of this node

	the_start := if dr_is_compound(rec) then wix_cum_start else wixnc_cum_start end if;
	return int_of_5(dr_load(rec)(the_start + (j - 1) * 5..the_start + j * 5 - 1));
	
end get_ch_cum;

procedure set_ch_cum(rec,j,cum_int);	-- set the integer cum value for the j-th child of this node

	the_start := if dr_is_compound(rec) then wix_cum_start else wixnc_cum_start end if;
	stg := dr_load(rec);		-- make sure that this record is loaded
	stg(the_start + (j - 1) * 5..the_start + j * 5 - 1) := stg_of_5(cum_int);
	dr_setrecbuf(rec,stg);dr_dirtify(rec);
	
end set_ch_cum;

procedure wix_get_cum2(rec);		-- get the record id string cum value of the final child of this node

	if (nc := num_childr(rec)) = 0 then return OM; end if;

	return get_ch_cum2(rec,nc);
	
end wix_get_cum2;

procedure get_ch_cum2(rec,j);	-- get the record id string cum value for the j-th child of this node
	
	the_start := if dr_is_compound(rec) then wix_cum2_start else wixnc_cum2_start end if;
	return dr_load(rec)(the_start + (j - 1) * 12..the_start + j * 12 - 1);
	
end get_ch_cum2;

procedure set_ch_cum2(rec,j,enc_wd);	-- set the record id string cum value for the j-th child of this node

	the_start := if dr_is_compound(rec) then wix_cum2_start else wixnc_cum2_start end if;
	stg := dr_load(rec);		-- make sure that this record is loaded
	stg(the_start + (j - 1) * 12..the_start + j * 12 - 1) := enc_wd + (12 - #enc_wd) * "\x00";
	dr_setrecbuf(rec,stg);dr_dirtify(rec);
	
end set_ch_cum2;

procedure vect_of_children(rec);					-- gets vector of children, as a string of 4-byte record numbers
	
	if not dr_is_compound(rec) then return ""; end if;
	nch := num_childr(rec);		-- number of children
        stg:=dr_load(rec);
	return stg(wix_ch_start..wix_ch_start - 1 + nch * 4);
	
end vect_of_children;

procedure set_vect_of_children(rec,stg);	-- sets vector of children, from a string of 4-byte record numbers
--print("set_vect_of_children: ",hexify(rec)," ",hexify(stg));
	if not dr_is_compound(rec) then print("Illegal effort to set vector of children for non_compound node: debug_val = ",debug_val); stop; end if;
	set_num_childr(rec,(nstg := #stg)/4);	-- set the number of children (also loads)
	missing := wix_cum_start - wix_ch_start - #stg;
--if missing < 0 then print("missing,wix_cum_start,wix_ch_start,#stg: ",missing," ",#stg," ",hexify(stg)); stop; end if;
	stg2:=dr_load(rec);
	stg2(wix_ch_start..wix_cum_start - 1) := (stg + missing * "\x00");
	dr_setrecbuf(rec,stg2);dr_dirtify(rec);
	
end set_vect_of_children;

procedure vect_of_cums(rec);					-- gets vector of cums, as a string of 5-byte fields
	
	the_start := if dr_is_compound(rec) then wix_cum_start else wixnc_cum_start end if;
	nch := num_childr(rec);		-- number of children
	return dr_load(rec)(the_start..the_start - 1 + nch * 5);
	
end vect_of_cums;

procedure set_vect_of_cums(rec,stg);	-- sets vector of cumulants, from a string of 5-byte record numbers

	the_start := if (ic := dr_is_compound(rec)) then wix_cum_start else wixnc_cum_start end if;
	the_end := if ic then wix_cum2_start else wixnc_cum2_start end if;
	missing := the_end - the_start - #stg;
	stg2:=dr_load(rec);		-- force load
 	stg2(the_start..the_end - 1) := (stg + missing * "\x00");
	dr_setrecbuf(rec,stg2);dr_dirtify(rec);
	
end set_vect_of_cums;

procedure vect_of_cums2(rec);					-- gets vector of cums, as a string of 4-byte fields
	
	the_start := if dr_is_compound(rec) then wix_cum2_start else wixnc_cum2_start end if;
	nch := num_childr(rec);		-- number of children
	return dr_load(rec)(the_start..the_start - 1 + nch * 12);
	
end vect_of_cums2;

procedure set_vect_of_cums2(rec,stg);	-- sets vector of second cums, from a string of 12-byte words

	the_start := if (ic := dr_is_compound(rec)) then wix_cum2_start else wixnc_cum2_start end if;
	the_end := if ic then wix_cum2_end else wixnc_cum2_end end if;
	missing := the_end - the_start + 1 - #stg;
if missing < 0 then print("Excessively long input stg to set_vect_of_cums2: ",the_start," ",the_end," ",#stg," ",stg); stop; end if;
	stg2:=dr_load(rec);		-- force load
	stg2(the_start..the_end) := (stg + missing * "\x00");
	dr_setrecbuf(rec,stg2);dr_dirtify(rec);
	
end set_vect_of_cums2;

procedure num_leaves(a_tree); 			-- debugging only 
	return if not dr_is_compound(a_tree) then num_childr(a_tree) 
			else 0 +/[num_leaves(voc(a_tree,j)): j in [1..num_childr(a_tree)]] end if;
end num_leaves;

procedure voc(rec,j);					-- n'th member of vector of children

	stg := dr_load(rec);					-- load this string
	if not dr_is_compound(rec) then print("Illegal effort to access vector of children for non_compound node"); stop; end if;
	cjstrt := (j - 1) * 4 + wix_ch_start; 
	return stg(cjstrt..cjstrt + 3);		-- return child rec
	
end voc;

procedure set_voc(rec,j,chrec);				-- set n'th member of vector of children

	cjstrt := (j - 1) * 4 + wix_ch_start; 
	stg:=dr_load(rec);		-- force load; then set the first character of the record
	if not dr_is_compound(rec) then print("Illegal effort to access element of vector of children for non_compound node"); stop; end if;
	
	stg(cjstrt..cjstrt + 3) := chrec;
	dr_setrecbuf(rec,stg);dr_dirtify(rec);

end set_voc;

procedure wix_make_from_tuple(t);	-- make nested representation from tuple
--print("make_from_tuple: ",t);	
	if #t <= wixnc_hi_lim then	-- put into just one section
		stg := dr_load(rec := wix_create());
		[icums,rids] := convert_tup_sect(t);		-- convert to cumulant string form
		set_vect_of_cums(rec,icums); set_vect_of_cums2(rec,rids);
		set_num_childr(rec,#t);		-- set the nominal number of children
		return rec;
	end if;
	
	last_used := 0;		-- the last component of t already incorporated into a tuple
	tx := [ ];
	for j in [1,wixnc_hi_lim..#t - 2 * (wixnc_hi_lim - 1)] loop
				-- put the data into a list of non_compound B_tree nodes, saving enough for at least
				-- one full final section
		rec := wix_create();
		[icums,rids] := convert_tup_sect(t(j..last_used := j + wixnc_hi_lim - 2));
						-- convert one section of input to cumulant string form
--print("convert_tup_sect B: ",wixnc_hi_lim," ",#rids);
		set_vect_of_cums(rec,icums); set_vect_of_cums2(rec,rids);
		set_num_childr(rec,wixnc_hi_lim - 1);		-- set the nominal number of children
		tx with:= rec;

	end loop;
	
	unusedo2 := (#t - last_used)/2;
	t1 := t(last_used + 1..last_used + unusedo2); t2 := t(last_used + unusedo2 + 1..);		
	rec := wix_create(); [icums,rids] := convert_tup_sect(t1); 
	set_num_childr(rec,unusedo2);		-- set the nominal number of children
	set_vect_of_cums(rec,icums); set_vect_of_cums2(rec,rids); tx with:= rec;

	rec := wix_create(); [icums,rids] := convert_tup_sect(t2); 
	set_vect_of_cums(rec,icums); set_vect_of_cums2(rec,rids); tx with:= rec;
	set_num_childr(rec,#rids/12);		-- set the nominal number of children

	t := tx;		-- use the converted t
		
	compound_now := false;		-- otherwise we must chop into sections; bottom level sections are not compound

	while (nt := #t) > wix_hi_lim loop
				-- build tree progressively from bottom, continuing as long as list of nodes obtained is too long
		sections := [t(j..j + wix_hi_lim - 2): j in [1,wix_hi_lim..nt - wix_hi_lim + 2]];	-- these are lists of nodes
	
		if (nt mod (wix_hi_lim - 1)) /= 0 then -- may have to rearrange last 2 pieces

			if #(piece := t((nrv := #sections) * (wix_hi_lim - 1) + 1..)) >= wix_low_lim then 
				sections with:= piece; 
			else  -- otherwise rearrange last 2 pieces
				ntp := #(twix_pieces := sections(nrv) + piece);
				sections(nrv) := twix_pieces(1..ntpo2 := ntp/2);
				sections with:= twix_pieces(ntpo2 + 1..);
			end if;

		end if;
	
		t := [ ];		-- recalculate the vector of items to work with
	
		for sec = sections(j) loop		-- convert each section into a tree node

			sec_node := dr_new_rec();		-- make a tree top for this tuple (i.e. this section)
			set_type(sec_node,wd_index_node_record);
											-- set the type of the record
			sec_stg := "" +/ sec;	-- convert the list of children to a string
			set_vect_of_children(sec_node,sec_stg);		-- set the list of children
			cumulate(sec_node);						-- initialize the cumulants
			t with:= sec_node;						-- assemble new vector of nodes
--print("sec_node: ",sec_node," ",hexify(dr_load(sec_node)));
		end loop;

		compound_now := true;		-- after first iteration, sections are not compound

	end loop;
	
	rec := dr_new_rec();		-- create a new, top level record
	
	t_stg := "" +/t;	-- convert the list of children to a string
	set_type(rec,wd_index_node_record);		-- at this point must be compound
	set_vect_of_children(rec,t_stg); 	-- these become the top-level children

	cumulate(rec);		-- initialize the final cumulants

	return rec; 
	
end wix_make_from_tuple;

procedure convert_tup_sect(t);		-- converts a tuple of pairs [wd,occslen] into a pair of strings
	
	cum := 0;		-- integer cumulant, developed below
	wds_stg := "" +/ [encode_wd(wd): [wd,occslen] in t];
	len_stg := "" +/ [stg_of_5(cum): [wd,occslen] in t | (cum := cum + occslen) >= 0];
--print("convert_tup_sect: ",#wds_stg," ",wds_stg," ",t," ",[#wd: [wd,-] in t]);
	return [len_stg,wds_stg]; 

end convert_tup_sect;

procedure wix_dump(rec);			-- get tuple from nested representation
				-- is compound representation or direct, depending on whether 'is_compound' flag is set
				-- note that this shows the vector of components, without their cumulants
				-- we ignore the cumulants in the tree nodes

var indent := 0;
return wix_dump_in(rec);			-- call inner workhorse

procedure wix_dump_in(rec);			-- inner workhorse

--print("wix_dump: ",hexify(dr_load(rec)));
	if int_of_4(rec) = 0 then return ["ZERO_NODE"]; end if;
	if dr_is_compound(rec) then 		-- compound case
		indent +:= 1; nc := num_childr(rec);
		stg :=  (["\n" + (indent * "   ") + "("] +/ [wix_dump_in(voc(rec,j)): j in [1..nc]]) 
					+ ["\n" + (indent * "   ")+ "[" + str(nc) + "]"  + decode_wd(wix_get_cum2(rec)) + ":" + str(wix_get_cum(rec)) + ")"]; 
		indent -:= 1;
		return stg;
	end if;						-- done with compound case

	if (ncr := num_childr(rec)) = 0 then return ["(,:0)"]; end if;
	t := [];				-- otherwise we must analyze the non-compound case
	prev := 0;
	for j in [1..ncr] loop
		int := (new := get_ch_cum(rec,j)) - prev; prev := new;
		decwd := decode_wd(get_ch_cum2(rec,j));
		t with := decwd + ":" + str(int);
	end loop;
	
	return ["\n" + (indent * "   ") + "("] + t + [decode_wd(wix_get_cum2(rec)) + ":" + str(wix_get_cum(rec)) + ")"];

end wix_dump_in;

end wix_dump;

procedure encode_wd(wd);		-- puts word into length-prefixed, self-defining form described above
--print("encode_wd: ",#(char(nc := #wd) + wd + zeroes11(nc + 1..))," ",#zeroes11," ",#wd); 
	if (nc := #wd) < 128 then return char(nc) + wd + 		-- encoding of string up to 128 bytes in length
		if nc <= 11 then zeroes11(nc + 1..) 
			elseif (ncmod := (nc + 1) mod 4) = 0 then "" else zeroes4(ncmod + 1..) end if; 
	 end if;

	len_chars := char(nc/256 + 128) + char(nc mod 256);
	return len_chars + wd + if (ncmod := (nc + 2) mod 4) = 0 then "" else zeroes4(ncmod + 1..) end if;

end encode_wd;		

procedure decode_wd(stg);		-- recovers word from length-prefixed, self-defining form described above
		-- the case of strings of more than 11 but no more than 128 bytes is represented twice in this
		-- preliminary version to allow the 'rest of the string' to be fetched if necessary

	if (wdlen := abs(stg(1))) <= 11 then 
		return stg(2..wdlen + 1);
	elseif wdlen < 128 then
		return stg(2..wdlen + 1);		-- but first get the rest of the string
	else
		wdlen := 256 * (wdlen - 128) + abs(stg(2));
		return stg(3..wdlen + 2);		-- but first get the rest of the string
	end if;

end decode_wd;

procedure int_of_12(stg);			-- convert a 12-byte string to an integer (for comparisons only)

	sum := 0; ns := #stg;
	for j in [1..12] loop sum := 256 * sum + if j > ns then 0 else abs(stg(j)) end if; end loop;

	return sum;

end int_of_12;

procedure wix_comp(rec,j);		-- fetch of component containing cumulant j
	return if (ccix := comp_cum_ix(rec,1,j)) = OM then OM else ccix(1..2) end if;	
end wix_comp;

procedure wix_comp2(rec,j);		-- fetch of component containing second cumulant j
	return if (ccix := comp_cum_ix(rec,2,j)) = OM then OM else ccix(1..2) end if;	
end wix_comp2;

procedure wix_comp_cum(rec,x);		-- fetch of x-th component, with cumulant
	return comp_cum_ix(rec,1,x);	
end wix_comp_cum;

procedure wix_comp_cum2(rec,x);		-- fetch of component containing second cumulant x, with cumulant
	return comp_cum_ix(rec,2,if x = OM then OM else encode_wd(x) end if);	
end wix_comp_cum2;

procedure comp_cum_ix(rec,srch_on,x);		-- fetch of x-th component by search on specified cumulant
									-- returns value in the form [rid,len,cum_len]
					-- component should be found by binary search
					-- search for the first index component with cumulant past
					-- the specified x; Return OM if there is none such.
								-- NOTE: this should be by binary search

							-- find the first node for which a cumulant >= j
	if x = OM then 				-- want last node
		j := num_childr(rec); 

		if srch_on = 1 then 		-- Note: only needed in non-compound case
			the_cum := get_ch_cum(rec,j); 
pass("wix_last1");
		else 
pass("wix_last2");
			the_cum := get_ch_cum2(rec,j); 
		end if;
			
	else
		if srch_on = 2 then 
			iofx := int_of_12(x);
pass("wix_nlast2");
		else 
pass("wix_nlast1");
		end if;
		if not (exists j in [1..num_childr(rec)] | 
			if srch_on = 1 then (the_cum := get_ch_cum(rec,j)) >= x else 
				int_of_12(the_cum := get_ch_cum2(rec,j)) >= iofx end if) then 
--print("******** return OM: ",x," ",nc := num_childr(rec)," ",wix_dump(rec)," ",if nc > 0 then get_ch_cum(rec,nc) else "NONE" end if); 
			return OM; 	-- desired node not found
		end if;
	end if;
		
	prev_cum := if j = 1 then 0 else get_ch_cum(rec,j - 1) end if;

	if not dr_is_compound(rec) then			 	-- if node is not compound we have what we want
		
		if srch_on = 1 then 	-- the integer cum was calculated above
pass("wix_nc1");
			return [decode_wd(get_ch_cum2(rec,j)),the_cum - prev_cum,the_cum];
		else  				-- the rec id was calculated above
			int_cum := get_ch_cum(rec,j);
pass("wix_nc2");
			return [decode_wd(the_cum),int_cum - prev_cum,int_cum];
		end if;
	end if;		-- otherwise we deal with the compound case
	
	res := comp_cum_ix(voc(rec,j),srch_on,if x = OM or srch_on = 2 then x else x - prev_cum end if);
			-- continue the search recursively

	[wd,noccs,lencum] := res;	-- decode the result returned recursively
	
	return [wd] + [noccs,prev_cum + lencum];

end comp_cum_ix;

procedure wix_set_comp(rw rec,w,x);-- assignment of the first component whose cumulant is at least w
	if x /= OM then x := [encode_wd(x(1)),x(2)]; end if;
	set_comp_ix(rec,1,w,x);
end wix_set_comp;

procedure wix_set_comp2(rw rec,w,x);-- assignment of the first component whose second cumulant is at least w
	if x /= OM then x := [encode_wd(x(1)),x(2)]; end if;
	if w = OM then set_comp_ix(rec,1,w,x); else set_comp_ix(rec,2,encode_wd(w),x); end if;
end wix_set_comp2;

procedure set_comp_ix(rw rec,srch_on,w,x);
	-- assignment of the first component whose specified cumulant is at least w; w must be in range
	-- we must first copy rec if its refcount is greater than 1, and transfer one reference
	-- from its old to its copied version. The leaves x are supplied as pairs [encoded_stg,number_of_occs]
	
	if refcount(int_of_4(rec)) > 1 then						-- must copy
pass("wix_set_copy");
		stg := dr_load(rec); new_r := dr_new_rec(); dr_setrecbuf(new_r,stg);dr_dirtify(new_r);
		increfs(new_r,1); incref(rec,-1); rec := new_r;		-- substitute copy for original
	end if;
	
	ic := dr_is_compound(rec); 
	if srch_on = 2 and w /= OM then wint := int_of_12(w); end if;
	ncr := num_childr(rec);
	
	if w = OM then			-- make change in last node

		srch_on := 1; w := get_ch_cum(rec,ix := ncr);           -- use search on first componet to find last child
		
		if ix = 0 then print("Change at end of empty tree is not allowed."); stop; end if;
	elseif not (exists ix in [1..ncr] |  
		if srch_on = 1 then get_ch_cum(rec,ix) >= w else int_of_12(get_ch_cum2(rec,ix)) >= wint end if) then 
		print("WIX - Search index " + str(w) + " out of range in assignment to cumulating vector " + hexify(rec)
		 		+ " " + str(ncr) + " " + str(ic) + " " + hexify(dr_load(rec))); stop;
	end if;
								-- get the local cumulant of the child
	if ic then 
		old_cum := wix_get_cum(voc(rec,ix));
pass("wix_nc1");
	else
pass("wix_comp1");
		old_cum := get_ch_cum(rec,ix) - if ix = 1 then 0 else get_ch_cum(rec,ix - 1) end if;
	end if;
			 
	prev_cum := if ix = 1 then 0 else get_ch_cum(rec,ix - 1) end if;
					
	if x /= OM then 			-- we are not dealing with a deletion

		if not ic then 			-- non-compound case; we must add the change in the leaf cumulant
								-- to the cumulant of all following nodes. 
			cum_change := x(2) - old_cum;
			update_cums(rec,ix,cum_change);		-- update the cums,starting with the given child

			set_ch_cum2(rec,ix,x(1));
				-- modify the cum of the changed component. Note that the following 
				-- second cumulants need not be changed. However, if ix references the 
				-- final child of rec, a cum2 entry in the parent of rec may need to be changed below.
pass("wix_ndel_nc");
			return;				-- done with this case
		end if;						-- otherwise we have the compound case
pass("wix_ndel_comp");		
		the_child := voc(rec,ix);				-- the next operation may copy the child
		set_comp_ix(the_child,srch_on,if srch_on = 1 then w - prev_cum else w end if,x);		
							-- make the change in the child
		cum_change := wix_get_cum(the_child) - old_cum;
		
		set_voc(rec,ix,the_child);		-- put the revised, possibly copied child back into position
			-- the 'update_cums' procedure which we call now must then start with the (properly set)
			-- cumulant of the preceding node, and then left_add the change in the the cumulant
			-- to the cumulant of this child to all the subsequent children. This assumes that 
			-- 		(new_d - old_d) + c + old_d + e = c + new_d + e
			-- for all cumulant values. This is obviously true for values using associative-commutative
			-- cumulator functions with an inverse, and also in the (string) case where a + b = b.
	
		update_cums(rec,ix,cum_change);			-- update the cums,starting with the given child
		
		if ix = ncr then 
		set_ch_cum2(rec,ix,wix_get_cum2(the_child));
pass("wix_ndel_comp_last");		
		else 
pass("wix_ndel_comp_nlast");		
		end if;
				-- the final cumulant of the_child might have been changed by 
				-- the preceding set_comp_ix(the_child,..) operation; see preceding comment.
		
--print("compound self,ix: ",wix_get_cum()," ",ix);
		return;				-- done with the non-deletion case
	
	end if;			-- otherwise we are dealing with a deletion
	
	if not dr_is_compound(rec) then 		-- non-compound case
pass("wix_del_nc");		

		if num_childr(rec) > 0 then		-- need not delete cumulant if no remaining children
pass("wix_del_nc_have");		
			stg := vect_of_cums(rec);				-- get the vector of cums
			stg((ix - 1) * 5 + 1..ix * 5) := "";		-- drop one element
			set_vect_of_cums(rec,stg);				-- put back into place
			stg := vect_of_cums2(rec);				-- get the second vector of cums
			stg((ix - 1) * 12 + 1..ix * 12) := "";		-- drop one element
			set_vect_of_cums2(rec,stg);				-- put back into place
		end if;

				-- delete the child from the string of descendants
		set_num_childr(rec,num_childr(rec) - 1);		-- count down the number of children

				-- delete the cumulant of the ix-th node. note that this has already been loaded
		cum_change := -old_cum;
		update_cums(rec,ix,cum_change);			-- update the cums,starting with the appropriate child
		return;				-- done with this case

	end if;				-- otherwise we are dealing with a deletion in a compound case
		
	the_child := voc(rec,ix);		-- get the child

	old_ch_leafsum := wix_get_cum(old_child := the_child);
	set_comp_ix(the_child,srch_on,if srch_on = 1 then w - prev_cum else w end if,OM);		-- make the deletion in the child
	new_ch_leafsum := wix_get_cum(the_child);
	set_voc(rec,ix,the_child := the_child);		-- re-insert the possibly modified child
	cum_change := new_ch_leafsum - old_ch_leafsum;
	update_cums(rec,ix,cum_change);			-- update the cums,starting with the given child
			-- since the last child may have been deleted, we also need to update the second cum
pass("wix_del_comp");		
	if ix = ncr then 
pass("wix_del_comp_last");		
		set_ch_cum2(rec,ix,wix_get_cum2(the_child)); 
	else
pass("wix_del_comp_nlast");		
	end if;
	
		-- now it is possible that the child has lost enough children to have fallen below the required wix_low_lim
		-- if this has happened, we attempt to share or join children with one of the adjacent siblings
	
	if num_childr(the_child) >= wix_low_lim then 	-- otherwise try to join or share
pass("wix_del_comp_enough");		
		return; 
	end if;
				
	if pull_from_left(rec,ix) or pull_from_right(rec,ix) then 
pass("wix_del_comp_canpull");		
		return; 
	end if;

	if join_with_left(rec,ix) or join_with_right(rec,ix) then 
pass("wix_del_comp_canjoin");		
		null; 
	end if;

			-- In the 'join' case, either the left or the right join must work,
			-- since in this compound case we must have at least one sibling.
			-- but we must check to see if the node being processed has fallen to
			-- just one child, and if it has, replace it by its single child.
	
	if num_childr(rec) > 1 then 
pass("wix_del_comp_npop");		
		return; 
	end if;
pass("wix_del_pop");		

	ch_rec := dr_load(the_ch := voc(rec,1)); dr_load(rec); dr_setrecbuf(rec,ch_rec); dr_dirtify(rec);
	
	if dr_is_compound(the_ch) then set_vect_of_children(the_ch,""); end if;		-- the children have all moved
	incref(the_ch,-1);		-- child data is inherited from single child, which loses a reference

end set_comp_ix;

procedure update_cums(rec,ix,cum_change);	-- update the cums of this tree,starting with the given child
				-- add cum_change to all subsequent children
	for j in [ix..nvc := num_childr(rec)] loop
		set_ch_cum(rec,j,cum_change + get_ch_cum(rec,j));
	end loop;
		
end update_cums;

procedure cumulate(rec);
	-- initalize the cumulants of a node whose children are either leaves or already initialized
	
	if not dr_is_compound(rec) then return; end if;		-- non-compound nodes are already cumulated

	the_cum := 0;

	for  j in [1..num_childr(rec)] loop
		nd := voc(rec,j);		-- get the j-th child
		nd_cum := wix_get_cum(nd);
				-- cumulant of the final child of the subnode, or occurence string length
		the_cum := the_cum + nd_cum;
		set_ch_cum(rec,j,the_cum);  		-- update the child's cumulant value
		nd_cum2 := wix_get_cum2(nd);
				-- cumulant2 of the final child of the subnode, or last element of occurence string
		set_ch_cum2(rec,j,nd_cum2);  		-- update the child's cumulant value
	end loop;

end cumulate;

procedure wix_insert(rw rec,j,x);		-- insertion before j-th component; or at the end if j = OM
	insert(rec,1,j,x);
end wix_insert;

procedure wix_insert2(rw rec,j,x);		-- insertion before component with second cumulant at least j;
	insert(rec,2,j,x);				-- or at the end if j = OM
end wix_insert2;

procedure insert(rw rec,srch_on,j,x);	-- insertion before j-th component with at least specified cumulant;
	tree_level := 0;		-- note that we are at the top of the tree
	x := [encode_wd(x(1)),x(2)]; if srch_on = 2 and j /= OM then j := encode_wd(j); end if;
	insert_in(rec,srch_on,j,x);	-- call the inner routine
end insert;

procedure insert_in(rw rec,srch_on,j,x);	-- inner recursion of insertion before j-th component 
									-- with at least specified cumulant; or at the end if j = OM
									-- component should be found by binary search
--print("insert_in: ",str(wix_dump(rec)));
	if refcount(int_of_4(rec)) > 1 then						-- must copy
pass("wix_in_copy");		
		stg := dr_load(rec); new_r := dr_new_rec(); dr_setrecbuf(new_r,stg);dr_dirtify(new_r);
		increfs(new_r,1); incref(rec,-1); rec := new_r;		-- substitute copy for original
	end if;
	
	result := OM; 	-- in case desired element not found
	ic := dr_is_compound(rec); ncr := num_childr(rec);
	the_cum := wix_get_cum(rec);	-- get final cumulant of this tree
	[x_cum2,x_cum] := x;	-- cumulant values of the leaf x
	
	if j /= OM then 		-- look for target node of insertion, if any

		if srch_on = 2 then 
			iofj := int_of_12(j); 
pass("wix_in_nend2");		
		else
pass("wix_in_nend1");		
		end if;
		
		if exists ix in [1..ncr] | 
			if srch_on = 1 then (cum := get_ch_cum(rec,ix)) >= j else 
				int_of_12(cum := get_ch_cum2(rec,ix)) >= iofj end if then 
			result := [ix,if ix = 1 then 0 else get_ch_cum(rec,ix - 1) end if,cum]; 
			if ic then nd := voc(rec,ix); end if;
pass("wix_in_nend3");		
		else 
pass("wix_in_end");		
			result := OM;
		end if;
	end if;
	
	if result = OM then 		-- we have insertion at the very end
		
		if not ic then -- simply append to vector
pass("wix_in_end_nc");		
			set_num_childr(rec,nvc := ncr + 1);
					-- add the cumulant of x to the present cumulant of this tree
			set_ch_cum(rec,nvc,the_cum := the_cum + x_cum);
			set_ch_cum2(rec,nvc,x_cum2);
--print("num_childr(rec): ",nvc," ",num_childr(rec)," ",ncr," ",wix_hi_lim + 1); 
			if tree_level > 0 or nvc <= wixnc_hi_lim then 			-- no need to split
pass("wix_in_end_nc_nos");		
				return; 
			end if;
						-- otherwise we must split, and becomes compound
pass("wix_in_end_nc_split");		
								-- note that in this case we are at the very top of the tree
			th := two_halves(rec);		-- get the two halves
			set_is_compound(rec,true);					-- note that it is indeed compound
			set_vect_of_children(rec,th);			-- split into 2 non-compound subtrees
			set_ch_cum(rec,1,wix_get_cum(voc(rec,1))); set_ch_cum(rec,2,the_cum);				
			set_ch_cum2(rec,1,wix_get_cum2(voc(rec,1))); set_ch_cum2(rec,2,wix_get_cum2(voc(rec,2)));				
			return;				-- done with this case

		end if;		-- otherwise we have insertion at the very end of a compound vector 
pass("wix_in_end_comp");				
		last_child:= voc(rec,nvc := num_childr(rec));		-- get the last child
		tree_level +:= 1;		-- down a level
		insert_in(last_child,srch_on,OM,x);				-- insert at the end of this last child
		tree_level -:= 1;		-- back up a level
		set_voc(rec,ncr,last_child);			-- insert the possibly modified child back into vect_of_children
							-- add the cumulant of x to the present cumulant of this tree
		set_ch_cum(rec,ncr,the_cum := the_cum + x_cum);
		set_ch_cum2(rec,ncr,x_cum2);
		
		if (if dr_is_compound(last_child) then wix_hi_lim else wixnc_hi_lim end if) >= num_childr(last_child) then
pass("wix_in_end_comp_nos");				
			return; 	-- no need to split the child
		end if;
						-- otherwise we must split the last child
pass("wix_in_end_comp_split");				
		split_node(rec,nvc);	-- split the nvc-th node into two.  we insert an empty node to the right
							-- of node nvc, and then move half the children of the nvc-th node into the new node	

		if tree_level > 0 or (nvc := num_childr(rec)) <= wix_hi_lim then 		-- no need to split this node
pass("wix_in_end_comp_nosthis");				
			return;				-- done with this case
		end if;
		-- otherwise we are at the very top of the tree, so we must split it into two parts and create a new tree level
pass("wix_in_end_comp_splitthis");							
--print("set_vect_of_children: insertion A: ",dr_is_compound(rec), if not dr_is_compound(rec) then str(wix_dump(rec)) else "" end if);
		set_vect_of_children(rec,two_halves(rec));
		set_ch_cum(rec,1,wix_get_cum(voc(rec,1))); set_ch_cum(rec,2,the_cum);				
		set_ch_cum2(rec,1,wix_get_cum2(voc(rec,1))); set_ch_cum2(rec,2,wix_get_cum2(voc(rec,2)));				

		return;				-- done with this case

	end if;		-- end of case of insertion at the very end
				-- in the remaining cases we have an insertion before one of our nodes
	
	 [ix,prev_cum,cum] := result;	-- decode the result returned, geting the insertion result and the preceding cumulant

	if not ic then -- insertion at appropriate position in non-compound vector
pass("wix_in_nend_nc");				
		the_cums := vect_of_cums(rec); the_cums2 := vect_of_cums2(rec); 
		the_cums(5 * ix - 4..5 * ix - 5) := 
			if ix = 1 then "\x00\x00\x00\x00\x00" else the_cums(5 * ix - 9..5 * ix - 5) end if;
		the_cums2(12 * ix - 11..12 * ix - 12) := x_cum2 + (12 - #x_cum2) * "\x00";
--print("#the_cums: ",#the_cums); if #the_cums > 70 then stop; end if;
		set_vect_of_cums(rec,the_cums);				-- make insertion into list of cums
		set_vect_of_cums2(rec,the_cums2);				-- make insertion into list of cums
		set_num_childr(rec,nvc := ncr + 1);	-- there is one more child
		update_cums(rec,ix,x_cum);					-- adjust the given and following cumulants
--print("inserted at position: ",ix," ",x," ",hexify(dr_load(rec)));
		if tree_level > 0 or nvc <= wixnc_hi_lim then		-- no need to split
pass("wix_in_nend_nc_nos");				
			return;				-- done with this case
		end if;				-- otherwise we must split, and becomes compound
pass("wix_in_nend_nc_split");				

		-- otherwise we are at the very top of the tree, so we must split it into two parts and create a new tree level
			
		th := two_halves(rec);				-- get the two halves
		set_is_compound(rec,true);			-- note that it is indeed compound
--print("set_vect_of_children: insertion B: ",dr_is_compound(rec), if not dr_is_compound(rec) then str(wix_dump(rec)) else "" end if);
		set_vect_of_children(rec,th);			-- split into 2 non-compound subtrees
		set_ch_cum(rec,1,wix_get_cum(voc(rec,1))); set_ch_cum(rec,2,the_cum + x_cum);				
		set_ch_cum2(rec,1,wix_get_cum2(voc(rec,1))); set_ch_cum2(rec,2,wix_get_cum2(voc(rec,2)));				
--print("just became compound: ",dr_is_compound(rec)," ",wix_dump(rec)); stop;
		return;									-- done with this case

	end if;		-- otherwise we deal with the compound case
pass("wix_in_nend_comp");				
	c := voc(rec,ix);		-- get the child into which the insertion will now be made
								-- and get the position in this child at which the insertion will be made
	tree_level +:= 1;		-- down a level
	insert_in(c,srch_on,if srch_on = 1 then j - prev_cum else j end if,x);		-- insert x into this child
	tree_level -:= 1;		-- back up a level
	set_voc(rec,ix,c);				-- put the possibly revised child back into position
	update_cums(rec,ix,x_cum);		-- adjust the given and following cumulants
	set_ch_cum2(rec,ix,wix_get_cum2(c)); 	-- adjust the second cumulant on record for the child
									-- which may have changed if the insertion was at the end of the child
	
	if (if dr_is_compound(c) then wix_hi_lim else wixnc_hi_lim end if) >= num_childr(c) then
pass("wix_in_nend_comp_nos");				
		return; 	-- no need to split the child
	end if;
pass("wix_in_nend_comp_split");				

								-- otherwise we must split the  child
	split_node(rec,ix);				-- split the child into two.  we insert an empty node to the right
								-- of node ix, and then move half the nodes into it	

	if tree_level > 0 or (nvc := num_childr(rec)) <= wix_hi_lim then 		-- no need to split this node
pass("wix_in_nend_comp_nosthis");				
		return;				-- done with this case
	end if;		-- otherwise we are at the very top of the tree, so we must split it into two parts and create a new tree level
		
--print("set_vect_of_children: insertion C: ",dr_is_compound(rec), if not dr_is_compound(rec) then str(wix_dump(rec)) else "" end if);
pass("wix_in_nend_comp_splitthis");				
	set_vect_of_children(rec,two_halves(rec));
	set_ch_cum(rec,1,wix_get_cum(voc(rec,1))); set_ch_cum(rec,2,the_cum + x_cum);				
	set_ch_cum2(rec,1,wix_get_cum2(voc(rec,1))); set_ch_cum2(rec,2,wix_get_cum2(voc(rec,2)));				

end insert_in;

procedure two_halves(rec);		-- split this tree into two halves
	-- the two nodes created share the children of the original tree, so  that the refcounts of 
	-- these children need no adjustment. The nodes created each have a refcount of 1.
	-- Note that this routine is only called if rec has no parent.

	the_type := if (ic := dr_is_compound(rec)) then wd_index_node_record else wd_index_node_ncr end if;
	u1 := dr_new_rec(); u2 := dr_new_rec();			-- make and initialize two subtrees
	set_type(u1,the_type); set_type(u2,the_type);	-- the halves are compound iff this tree is compound

	-- we must subtract the cumulant of the last retained child from all the children that move
	-- to get the cumulant of the left node
	hnvc := (nvc := num_childr(rec))/2; cum_last_retained := get_ch_cum(rec,hnvc);
	
	for j in [hnvc + 1..nvc] loop			-- subtract this from the cumulant of each child that will move
		set_ch_cum(rec,j,get_ch_cum(rec,j) - cum_last_retained);
	end loop;
	
	vocums := vect_of_cums(rec);		-- get the vector of cums
	vocums2 := vect_of_cums2(rec);		-- get the vector of cums

	if ic then 
pass("wix_halves_nc");				
		set_vect_of_children(u1,(voch := vect_of_children(rec))(1..4 * hnvc)); 
	else
pass("wix_halves_comp");				
		set_num_childr(u1,hnvc);		-- set the number of children of u1
	end if;

	set_vect_of_cums(u1,vocums(1..5 * hnvc));			-- u1 gets half the children and cums
	set_vect_of_cums2(u1,vocums2(1..12 * hnvc));			-- u1 gets half the children and cums
	
	set_vect_of_cums(u2,vocums(5 * hnvc + 1..));	-- the second half inherits adjusted cumulants from the original tree
	set_vect_of_cums2(u2,vocums2(12 * hnvc + 1..));			-- likewise for the second cums
	set_num_childr(u1,hnvc);		-- set the number of children of u1
	if ic then 
		set_vect_of_children(u2,voch(4 * hnvc + 1..));  -- u2 gets the other half of  the children
	else
		set_num_childr(u2,nvc - hnvc);		-- set the number of children of u2
	end if;

--print("two_halves: ",str(wix_dump(u1)),"\n",str(wix_dump(u2)),"\n",hexify(voch(4 * hnvc + 1..)),"\n",hexify(dr_load(u2)));
	return u1 + u2;
				-- assemble the two nodes of the new compound tree; return as a string

end two_halves;

procedure hpull_from_left(rec,k);		-- split children with left sibling

	if k = 1 or num_childr(voc(rec,k - 1)) <= wix_low_lim then 
		return false; 
	end if;
pass("wix_pull_left");				
	share_right(rec,k - 1);
	return true;

end hpull_from_left;

procedure hpull_from_right(rec,k);	-- split children with right sibling

	if k >= (nrv := num_childr(rec)) or num_childr(voc(rec,k + 1)) <= wix_low_lim then
		return false;
	end if;
pass("wix_pull_right");				
	share_right(rec,k); 
	return true;

end hpull_from_right;

procedure hshare_right(rec,k);	-- share children with right-hand sibling
	
		-- we divide the children of the k-th node, together with those of the k+1'st,
		-- into two roughly equal groups, and make these the k-th and k+1'st nodes. The
		-- cumulative totals must be adjusted in the k-th node, in the
		-- children moved between nodes, and in the children of the k+1'st node    
	-- this routine must first copy the nodes among which children will move, if they have more than 1 reference.
	-- but it does not change the number of references to the children, so that their refcounts need no adjustment
--print("share_right: ",k," ",str(wix_dump(rec)));		
	if (ic := dr_is_compound(ndk := voc(rec,k)))  then 	-- a compound node is involved in the sharing
pass("wix_share_nc");				
		nchkp1 := #(rkp1 := vect_of_children(ndkp1 := voc(rec,k + 1)))/4;
		nchk := #(rk := vect_of_children(ndk))/4;	-- get the two groups of children, and their lengths
	else 
pass("wix_share_comp");				
		nchkp1 := num_childr(ndkp1 := voc(rec,k + 1)); nchk := num_childr(ndk);
	end if;
	
	numleft := (nchk + nchkp1)/2;	-- half the children; the left-hand will get this number of children
	
	if refcount(int_of_4(ndkp1)) > 1 then						-- must copy
pass("wix_share_copy");				
		stg := dr_load(ndkp1); new_r := dr_new_rec(); dr_setrecbuf(new_r,stg);dr_dirtify(new_r);
		incref(ndkp1,-1); ndkp1 := new_r;		-- substitute copy for original
		increfs(new_r,1); set_voc(rec,k + 1,new_r);
	end if;

	if refcount(int_of_4(ndk)) > 1 then						-- must copy
pass("wix_share_copy2");				
		stg := dr_load(ndk); new_r := dr_new_rec(); dr_setrecbuf(new_r,stg);dr_dirtify(new_r);
		incref(ndk,-1); ndk := new_r;		-- substitute copy for original
		increfs(new_r,1); set_voc(rec,k,new_r);
	end if;
	
	if numleft > nchk then		-- children will move left
pass("wix_share_move_left");						
		num_mov := numleft - nchk;		-- the number that will move left
--print("move left: ",num_mov," ",hexify(dr_load(ndk)),"\n",hexify(dr_load(ndkp1)));		
			-- we must subtract the cumulant of the last child moving left
			-- from the cumulants of all the right-hand children which do not move, 
			-- and must add this to the cumulant of the k-th node. We must also
			-- add the cumulant of the last left-hand child of ndk to the cumulants of all 
			-- the right-hand children which do move. 

		ndk_cum := get_ch_cum(rec,k);			-- get the cumulant of ndk
		right_cum := wix_get_cum(ndk);			-- cumulant of the last child of ndk

		moved_cum := get_ch_cum(ndkp1,num_mov);		-- cumulant of the last child of ndkp1 that moves 
		set_ch_cum(rec,k,moved_cum + ndk_cum);		-- add moved_cum to the cumulant of the k-th node
		set_ch_cum2(rec,k,get_ch_cum2(ndkp1,num_mov));	-- correct the second cumulant of the k-th node
		
		for j in [1..num_mov] loop
			set_ch_cum(ndkp1,j,right_cum + get_ch_cum(ndkp1,j));
		end loop;
		
		for j in [num_mov + 1..nchkp1] loop
			set_ch_cum(ndkp1,j,get_ch_cum(ndkp1,j) - moved_cum);
		end loop;

											-- and now we must move the corresponding cums
		cumvp1 := vect_of_cums(ndkp1);			-- second vector of cums
--print("ndkp1: ",hexify(ndkp1)," ",hexify(dr_load(ndkp1))); stop;
		set_vect_of_cums(ndk,vect_of_cums(ndk) + cumvp1(1..num_mov * 5));		-- move the cums in
		set_vect_of_cums(ndkp1,cumvp1(num_mov * 5 + 1..));					-- move the cums out
			-- since the number of cums of ndkp1 is defined by its number of children, we need not edit that list 
		cumvp1 := vect_of_cums2(ndkp1);			-- second vector of second cums
--print("ndkp1: ",hexify(ndkp1)," ",hexify(dr_load(ndkp1))); stop;
		set_vect_of_cums2(ndk,vect_of_cums2(ndk) + cumvp1(1..num_mov * 12));		-- move the cums in
		set_vect_of_cums2(ndkp1,cumvp1(num_mov * 12 + 1..));					-- move the cums out
		
		if ic then 		-- if the nodes are compound we must move children in addition to cumulants
			set_vect_of_children(ndk,rk + rkp1(1..4 * num_mov));		-- now actually move the children
			set_vect_of_children(ndkp1,rkp1(4 * num_mov + 1..));
		else 		-- not compound; must adjust the number of children
			set_num_childr(ndk,nchk + num_mov); set_num_childr(ndkp1,nchkp1 - num_mov);
		end if;
--print("move the children: ",rk," ",rkp1," ",num_mov); 

	else						-- children will move right
pass("wix_share_move_right");						
				-- we must subtract the cumulant of the last remaining child 
				-- from that of each of the children moving right. The remaining cumulant of
				-- the last child moving right must then be added to the cumulants of
				-- all the original children of the (k + 1)-st node
--print("numleft: ",numleft);	
		rem_left_cum := get_ch_cum(ndk,numleft);		-- cumulant of the last remaining child of ndk

		for j in [numleft + 1..nchk] loop	-- subtract this from the cum of all the nodes moving right
			set_ch_cum(ndk,j,get_ch_cum(ndk,j) - rem_left_cum);
		end loop;
		
		total_moved_cum := get_ch_cum(ndk,nchk);		-- get the cumulant of the last node moving right
		
		for j in [1..nchkp1] loop	-- add this to the cum of all the children of the (k + 1)-st node
			set_ch_cum(ndkp1,j,total_moved_cum + get_ch_cum(ndkp1,j));
		end loop;

		set_ch_cum(rec,k,get_ch_cum(rec,k) - total_moved_cum);
				-- the cumulant of the last node moving right must be subtracted from the cumulant of the k-th node
		set_ch_cum2(rec,k,get_ch_cum2(ndk,numleft));	-- update the second cum of the moved node
											-- and now we must move the corresponding cums
		cumv := vect_of_cums(ndk);				-- first vector of cums
		cumvp1 := vect_of_cums(ndkp1);			-- second vector of cums
		set_vect_of_cums(ndkp1,cumv(5 * numleft + 1..5 * nchk) + vect_of_cums(ndkp1));		-- move the cums
			-- since the number of cums of ndk is defined by its number of children, we need not edit that list 
		cumv := vect_of_cums2(ndk);				-- first vector of cums
		cumvp1 := vect_of_cums2(ndkp1);			-- second vector of cums
		set_vect_of_cums2(ndkp1,cumv(12 * numleft + 1..12 * nchk) + vect_of_cums2(ndkp1));		-- move the cums

		if ic then 		-- if the nodes are compound we must move children in addition to cumulants
			set_vect_of_children(ndk,rk(1..4 * numleft));		-- now actually move the children
			set_vect_of_children(voc(rec,k + 1),rk(4 * numleft + 1..) + rkp1);
		else 		-- not compound; must adjust the number of children
			set_num_childr(ndk,numleft); set_num_childr(ndkp1,nchk + nchkp1 - numleft);