OpenStreetMap Schweiz, https://www.osm.ch/
Neuchâtel is about 90 mins by train from the international airports in Geneva, Zurich, and Basel. Trains from Geneva Airport run directly once hourly (last train to reach Neuchâtel about 9 pm). Trains from Zurich Airport run twice hourly directly or via Zurich central (until about 10 pm). From Basel EuroAirport, take the shuttle bus twice hourly to Basel SBB and then a train via Olten or Biel/Bienne (until about 9.30 pm). Tickets are CHF 50–60 one way; early bird fares are available through sbb.ch (watch out for the black % triangle).
While Neuchâtel is small enough to be walkable, it is built into a hill—getting to some locations can count as a full work-out. The conference venue is at lake-level, as is the inner city. The train station Neuchâtel Gare CFF is uphill (5–10 mins walk to the university and 10–15 mins back). It is connected to the university Swiss-style via a cable car (Fun’ambule) which leaves from the station’s concourse every three minutes. The buses 101 and 121 stop outside the main building (Stop Université), from which it is a short walk to the Aula and the FLSH building.
If you are staying in a hotel, you will be issued with a local transportation ticket for unlimited travel on public transport throughout the canton. If you arrange for private accommodation, bus/cable car rides are CHF 4.20 for a single ticket (zones 10/11, covering the city of Neuchâtel). Short bus trips are CHF 2.10 (court parcours); there is a list at the top of each vending machine listing the destinations which are eligible for a short trip from that stop. Multi-rider tickets are CHF 21 (6 for the price of 5; carte multicourses). Multi-riders need to be validated before each trip via the machines at the bus stops. Note that tickets are only available from vending machines; you cannot buy them from bus drivers.
For more information on getting to Neuchâtel from further afield in the canton, check transn.ch or sbb.ch. Hiring a bike might be an option; check out neuchatelroule.ch, which has a self-service drop-off spot right next to the conference venue (spot 117 UniLac).