WHY ADVANCED ALGORITHMS??

        The need for efficient algorithms arises in every area of computer science. Advanced algorithm gives a general  understanding of efficient algorithms and gives a better understanding for how to design and analyze efficient algorithms.They represent simplified mathematical ideas for solving complicated problems. 

          Advanced algorithm helps in knowing the techniques that apply broadly in the design of efficient algorithms and study their applications in a wide range of application domains and computational models. The biggest difference from undergraduate algorithms is extensive use of ideas such as randomness, approximation, high dimensional geometry,  which are increasingly important in most applications. The notions such as algorithm design in face of uncertainty, approaches to handle big data, handling intractability, heuristic approaches, etc are encountered.

THE HAFAS SYSTEM

The well-informed finds his way and is more mobile. The more data available, the better and - even more important - more detailed is the information provided for the passengers. Any data - timetable data, geographical data and real-time data - can be fed into HAFAS and included for the journey information. Thus HAFAS is a door-to-door information that does not end at points in the network. As a matter of fact, passengers do not travel only from stop to stop, and their journeys will not always go according to plan.

Start and Destination Search 

Meet and understand customer requirements 

 At the beginning of each journey planning, the starting point and destination have to be determined. What sounds simple and logical often is not in practice. For example, if a customer wants to make stops along the way, if he does short distances also on foot or if he takes a different route for the way back. Such trips need to be specified to concrete starting- and end points or stops – something which overstrains too many users, often because they do not know the name of a station or of an exact address. 

Search for starting point and final destination: For every search result a map pops up when klicking on the info-icon. By which mode of transport a station is served gets clear via the toolbar of the map.

Fault tolerant search in real-time

But even if the customer exactly knows places or stops, what he actually enters into the search might still be imprecise. Examples for that would be spelling mistakes or mistakes in the order of names of places (Hannover, Lister Strasse vs. Lister Strasse, Hannover). In addition, foreign language letters can only be entered with difficulty on a German keyboard or not at all. Yet, unicode support in the search allows HAFAS to interpret these characters of foreign languages correctly. HAFAS also provides plausible results when users choose different spellings for the same station, as for example Frankfurt (Main) main station or Frankfurt am Main or Frankfurt (Main).

All-type search – robust search, reliable results

The search behaviour of many customers has been affected by what they got used to by Google: all-type search in just one field, no matter whether a bus stop, an address or a POI is requested. Because it is customer friendly, if passengers do not have to choose the category to search in in advance and they can simply start typing. Whether an address, POI, station, phone number or license plate is entered – the HAFAS algorithm quickly calculates a convenient result out of the large number of possible entries.

Type-ahead search – quick entry with HAFAS Suggest

Even while the user is still entering letters, HAFAS Suggest automatically completes the search by making suggestions. In this way, the customer immediately receives a feedback to his query. The lengthy process of search input,  suggestions, new search input, etc. is reduced. This especially spares users of mobile devices a strenuous search entry. However, this only works if the algorithm is efficient and fast and thus efficiently delivers results.

HAFAS pattern matching

The list of results is calculated with highly efficient, fault-tolerant algorithmic process. The presentation of the search results in alphabetical order sounds useful – however, in practice this leads to results in a long list which mostly does not put the best results in the first place. The HAFAS algorithm sets priorities differently in applying various sort criteria and for example

• prefers stations over addresses (unless the input of a street number indicates an address search)
• prefers larger over smaller stops or stations
• gives higher weight to places having the same prefix as the search entry.

If no clear result can be determined, HAFAS presents a selection list of possible hits.

HAFAS customisation on the part of the transport operator

HAFAS clients can define individual replacement rules and filters for the HAFAS search on their website. Possible are automatically generated abbreviations as from "Hauptbahnhof" ("Hbf") or "street" ("str.").

The type-ahead search and the full-search function can be adapted to the needs of transport operators: So, for example, the type-ahead search can be restricted to only those stations that are actually served by the provider.

HAFAS customisation on the part of the passenger

The passenger/user may filter the displayed search result by including or excluding POI, addresses, stops, classes of products (and more). For example it is possible to restrict the type-ahead search on stops that are served by the operator. However, station attribute filters are applied if the customer wants to see only stations equipped with lifts.

Also, travel information can be even more customer-friendly, if the search takes favourite locations or the current position into account. Thus, the nearest stops are considered.

HAFAS also adopts product classes of the starting point when searching for destinations. If the passenger starts his trip from a local bus stop, HAFAS assumes a short-distance connection. If the search starts from a central station, it makes sense to list main stations first also for the place of arrival.

In this way, HAFAS supports transport operators to understand passengers' needs and even predict them by interpreting search entries in context and automatically suggesting solutions for the customers.