## 4 Our Modeling Approach
### The Power of Hierarchical Modeling
\begin{tabular}{c l l l l} \hline \hline
**Case** & **Activity** & **Date/Time** & **Actors** &
\begin{tabular}{l} **Other Details** \\ **(Cost, Shipping Address, Weight...)** \\ \end{tabular} \\ \hline
1 & Reg. Order & 01/09, 8:30 & JS & 50\(\c\), Iasonidou 3, Thermi, 40 Kg... \\  & Decide \"Heavy\" & 01/09, 8:50 & SC & \\  & Decide \"Short\" & 01/09, 9:02 & SC & \\  & Make shipment plan & 01/09, 9:18 & DD & \\  & Check available resources & 01/09, 10:00 & DD & \\  & Ship packet & 01/09, 12:00, & FG, car & \\  & Return & 01/09, 12:40, & FG, car & \\ \hline
2 & Reg. Order & 01/09, 8:45 & KN & 150\(\c\), 25 Martiou 3, Veroia, 150 Kg... \\  & Decide \"Long\" & 01/09, 9:00 & CP & \\  & Decide \"Heavy\" & 01/09, 9:12 & CP & \\  & Make shipment plan & 01/09, 9:52 & GI & \\  & Check available resources & 01/09, 10:30 & GI & \\  & Ship packet & 01/09, 13:00, & XX \& FS, lorry & \\  & Return & 01/09, 15:40, & XX \& FS, lorry & \\ \hline \hline \(\vdots\) & \(\vdots\) & \(\vdots\) & \(\vdots\) & \(\vdots\) \\ \(\vdots\) & \(\vdots\) & \(\vdots\) & \(\vdots\) & \(\vdots\) \\ \(\vdots\) & \(\vdots\) & \(\vdots\) & \(\vdots\) & \(\vdots\) \\ \(\vdots\) & \(\vdots\) & \(\vdots\) & \(\vdots\) & \(\vdots\) \\ \hline
188 & Reg. Order & 14/09, 8:52 & JS & 70\(\c\), 22 D. Vlachou, Naousa, 1 Kg... \\  & Decide \"Light\" & 14/09, 9:19 & CP & \\  & Decide \"Long\" & 14/09, 9:29 & SC & \\  & Make shipment plan & 14/09, 9:47 & GI & \\  & Check available resources & 14/09, 10:02 & GI & \\  & Ship packet & 14/09, 10:08, & AS, motorbike & \\  & Return & 14/09, 10:18, & AS, motorbike & \\ \hline
189 & Reg. Order & 14/09, 9:21 & JS & 5\(\c\), 11 Solonos, Perea, 4 Kg... \\  & Decide \"Short\" & 14/09, 9:32 & CP & \\  & Decide \"Light\" & 14/09, 9:40 & SC & \\  & Make shipment plan & 14/09, 11:00 & DD & \\  & Check available resources & 14/09, 11:12 & DD & \\  & Ship packet & 14/09, 14:00, & PG, car & \\  & Return & 14/09, 16:32, & PG, car & \\ \hline \hline \end{tabular}   
In addition, we were kindly provided with some general information regarding the branch structure, which includes:  
* Three officers, JS, SC, and CP, who are responsible for registering the orders, check the packet weight and shipment address and, based on this information, decide if the packet is \"heavy\" or \"light\" and if the distance is \"short\" or \"long\". * Two managers, DD and GI, who decide about the shipment plan and check the available resources (drivers and vehicles). * Ten experienced drivers, who are entitled to drive cars andlorries. In the part shown here, two instances of \"experienced driver\" are FG, XX, and PG. * Fifteen inexperienced drivers, who are entitled to drive cars and motorbikes, but also accompany experienced drivers when packets are transferred over long distances by lorry. In the dataset shown, PS and AS are examples of \"inexperienced drivers\". In addition, each driver is entitled to a break after each shipment, which can last from 5 min up to 1 h, depending on the distance they have traveled. Finally, more than one shipments are attached to each shipment plan, but our model is not affected by that fact. Now, we code the activities as follows: \begin{tabular}{l c c c c c c c c c} \hline \hline
**Activity** & **Encoded as Event** & **Actors** & **Other Details** \\ \hline Reg. Order & \(E_{1}\) & JS, SC, CP & \(\cdots\) \\ Decide \"heavy\" & \(E_{2}\) & JS, SC, CP & \(\cdots\) \\ Decide \"light\" & \(E_{3}\) & JS, SC, CP & \(\cdots\) \\ Decide \"long\" & \(E_{4}\) & JS, SC, CP & \(\cdots\) \\ Decide \"short\" & \(E_{5}\) & JS, SC, CP & \(\cdots\) \\ Make shipment plan & \(E_{6}\) & DD, GI & \(\cdots\) \\ Check available resources & \(E_{7}\) & DD, GI & \(\cdots\) \\ Ship packet & \(E_{8}\) & All driver and vehicle instances & \(\cdots\) \\ Drivers take a break & \(E_{9}\) & All driver instances & \(\cdots\) \\ \hline \hline \end{tabular}   
Based on this encoding, we can create the EST for our log file, as shown in Table 3.  
The CRT for our courier example is given in Table 4.  
Now, let us examine Tables 3 and 4 in detail.