public int getSimpleNode(int vfalse, int vtrue, int start, int end) {
		if (start>end || start<0 || end>=nbval) {
			return -1;
		}
		if (nbval == 2) {
			if (start != end) {
				return vtrue;
			}
			if (start == 0) {
				return store.getNode(order, vtrue, vfalse);
			}
			return store.getNode(order, vfalse, vtrue);
		}
		
		
		int[] children = new int[nbval];
		for (int i=0 ; i<start ; i++) {
			children[i] = vfalse;
		}
		for (int i=start ; i<=end ; i++) {
			children[i] = vtrue;
		}
		for (int i=end+1 ; i<nbval ; i++) {
			children[i] = vfalse;
		}
		return store.getNode(order, children);
	}