string dynamicEMTraining(string theNet, string trainingSet){ 
 // open the data set:
	 DSL_dataset ds;
	 if (ds.ReadFile(trainingSet.c_str()) != DSL_OKAY) {
		cout << "Cannot read data file... exiting." << endl;
		exit(1);
	 }
	 
	 // open the network:
	 DSL_network net;
	 if (net.ReadFile(theNet.c_str(), DSL_XDSL_FORMAT) != DSL_OKAY) {
		cout << "Cannot read network... exiting." << endl;
		exit(1);
	 }
	 
	 // match the data set and the network (variables):
	 vector<DSL_datasetMatch> dsMap(ds.GetNumberOfVariables());
	 int varCnt = 0;  // the number of variables occuring both in the data set and the network
	 for (int i = 0; i < ds.GetNumberOfVariables(); i++) {
		string id = ds.GetId(i);
		const char* idc = id.c_str();
		
		bool done = false;
		for (int j = 0; j < (int) strlen(idc) && !done; j++) {
		   if (idc[j] == '_') {
			  char* nodeId = (char*) malloc((j+1) * sizeof(char));
			  strncpy(nodeId, idc, j);
			  nodeId[j] = '\0';
			  
			  int nodeHdl = net.FindNode(nodeId);
			  if (nodeHdl >= 0) {
				 DSL_intArray orders;
				 net.GetTemporalOrders(nodeHdl, orders);
				 
				 dsMap[varCnt].node   = nodeHdl;
				 dsMap[varCnt].slice  = atoi(idc + j + 1);
				 dsMap[varCnt].column = i;
				 varCnt++;
				 
				 free(nodeId);
				 done = true;
			  }
		   }
		}
		if (!done) {
		   int nodeHdl = net.FindNode(idc);
		   if (nodeHdl >= 0) {
			  dsMap[varCnt].node   = nodeHdl;
			  dsMap[varCnt].slice  = 0;
			  dsMap[varCnt].column = i;
			  varCnt++;
		   }
		}
	 }
	 dsMap.resize(varCnt);
	 
	 // match the data set and the network (states):
	 for (int i = 0; i < dsMap.size(); i++) {
		DSL_datasetMatch &m = dsMap[i];
		int nodeHdl = m.node;
		int colIdx = m.column;
		
		DSL_idArray* ids = net.GetNode(nodeHdl)->Definition()->GetOutcomesNames();
		const DSL_datasetVarInfo &varInfo = ds.GetVariableInfo(colIdx);
		const vector<string> &stateNames = varInfo.stateNames;
		vector<int> map(stateNames.size(), -1);
		for (int j = 0; j < (int) stateNames.size(); j++) {
		   const char* id = stateNames[j].c_str();
		   for (int k = 0; k < ids->NumItems(); k++) {
			  char* tmpid = (*ids)[k];
			  if (!strcmp(id, tmpid)) {
				 map[j] = k;
			  }
		   }
		}
		for (int k = 0; k < ds.GetNumberOfRecords(); k++) {
		   if (ds.GetInt(colIdx, k) >= 0) {
			  ds.SetInt(colIdx, k, map[ds.GetInt(colIdx, k)]);
		   }
		}
	}
	
	// learn parameters:
	DSL_em em;
	if (em.Learn(ds, net, dsMap) != DSL_OKAY) {
		cout << "Cannot learn parameters... exiting." << endl;
		exit(1);
	}
	
	net.WriteFile((theNet.insert(theNet.find_last_of("/") + 1, "res_")).c_str(), DSL_XDSL_FORMAT);
	
	return theNet;
}