We describe our 2018 Alexa prize system (called ‘Alana’) which consists of an ensemble of bots, combining rule-based and machine learning systems. This paper reports on the version of the system developed and evaluated in the semifinals of the 2018 competition (i.e. up to 15 August 2018), but not on subsequent enhancements. The main advances over our 2017 Alana system are:
We also present several ablation studies that measure the performance contributions of specific features (e.g. use of Ontology-bot, Reddit-bot, rule-based systems, etc). We find that these features increase overall system performance. Our final score, namely averaged user ratings over the whole semi-finals period, was 3.4. We were also able to achieve long dialogues (average around 11 turns and 2.20 minutes) during the semi-finals period.