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Title: I love your chain mail! Making knights smile in a fantasy game world

Paper content:
Dialogue research tends to distinguish between chit-chat and goal-oriented tasks.
While the former is arguably more naturalistic and has a wider use of language, the latter has clearer metrics and a more straightforward learning signal.
Humans effortlessly combine the two, and engage in chit-chat for example with the goal of exchanging information or eliciting a specific response.
Here, we bridge the divide between these two domains in the setting of a rich multi-player text-based fantasy environment where agents and humans engage in both actions and dialogue.
Specifically, we train a goal-oriented model with reinforcement learning via self-play against an imitation-learned chit-chat model with two new approaches: the policy either learns to pick a topic or learns to pick an utterance given the top-k utterances.
We show that both models outperform a strong inverse model baseline and can converse naturally with their dialogue partner in order to achieve goals.
In the literature on artificial dialogue agents, a distinction is often made between "goal-oriented" dialogue, where an agent is tasked with filling slots or otherwise obtaining or disseminating specified information from the user to help complete a task, and "chit-chat", where an agent should imitate human small talk.
Modeling goal-oriented dialogue can have advantages over chit-chat imitation as it gives clearer metrics of success and perhaps more meaningful learning signals; but goal-oriented dialogue data is often more specialized, covering only a narrow slice of natural language.
Current goal-oriented datasets study setting like booking restaurants or airline tickets, or obtaining weather information, as standalone tasks (Raux et al., 2005; Henderson et al., 2014; Bordes et al., 2017; El Asri et al., 2017; Budzianowski et al., 2018) .
Chit-chat agents, by contrast, might focus on coarse statistical regularities of dialogue data without accurately modeling the underlying "meaning"; but the data often covers a much wider space of natural language.
For example, Twitter or Reddit chitchat tasks (Li et al., 2016a; Yang et al., 2018; Mazaré et al., 2018 ) cover a huge spectrum of language and diverse topics.
Chit-chat and goal-oriented dialogue are not mutually exclusive: when humans engage in chit-chat, their aim is to exchange information, or to elicit specific responses from their partners.
Modeling such goals, however, is made difficult by the fact that it requires large amounts of world knowledge, and that goals in real life are implicit.
In this work, we study goal-oriented dialogue agents in the setting of a multi-player text-based fantasy environment (Urbanek et al., 2019) .
The environment is built on top of a game engine that grounds actions and reference objects, and thus codifies a body of world-knowledge.
Although the interactions between objects and characters are simulated, the choice and types of interactions, the text used to describe them, and the dialogues between characters, are "natural" and wide-ranging, having been collected from human crowdworkers.
We define the general task of, given a particular character in a particular scenario (location, set of objects and other characters to interact with) to conduct open-ended dialogue such that a given action is executed in the future by their dialogue partner.
The given action could be an emote action (smile, laugh, ponder, . . . ), or a game action (wear chain mail, drink mead, put glass on table, . . . ).
The richness of the environment means that there are a huge set of possible tasks and scenarios in which to achieve a wide range of actions.
Thus, this task is ideally suited for bridging the divide between goal-oriented and chit-chat dialogue, combining clearer metrics and learning signals on the one hand, with the richness and complexity of situated but open-domain natural language on the other.
Figure 1 : Example episode from the LIGHT dataset, consisting of an environment (location setting, characters with given personas, objects), utterances and game actions.
There are 10,777 such humanhuman gameplay episodes, and a rich world of 663 locations, 1755 characters and 3462 objects.
We train models to achieve these tasks using reinforcement learning (RL) and a type of self-play between two agents.
The first agent, which we call the environment agent, is trained with imitation learning on human-human interactions (game actions, utterances and emotes) and subsequently kept fixed.
The second agent, the RL agent, is trained to conduct dialogue given the goal, and the two agents interact within a given environment until the goal is either reached or a given number of turns has expired.
At that point, rewards are given, and the RL agent is updated.
We compare agents that have been trained to imitate human actions given a goal (an "inverse model") to two different RL approaches: optimizing actions with latent discrete variables (topics), or via rewarding actions sampled from the model (via the top-K outputs).
We show that both types of RL agent are able to learn effectively, outperforming the inverse model approach or a vanilla chit-chat imitation baseline, and can converse naturally with their dialogue partner to achieve goals.
In this paper, we investigate agents that can interact (speak or act) and can achieve goals in a rich world with diverse language, bridging the gap between chit-chat and goal-oriented dialogue.
We achieve this by defining a task for an agent, where the goal is for the other player to execute a particular action.
We explore two reinforcement learning based approaches to solve this task: the policy either learns to pick a topic or learns to pick an utterance given the top K utterances, and compare them against a strong baseline trained to imitate chit-chat.
We show that these approaches effectively learn dialogue strategies that lead to successful completion of goals, while producing natural chat.
Future work should explore further RL algorithms for agents that can act and speak in natural language at scale in our proposed rich task environment, and we expect further advancements.

assistant: text: Agents interact (speak, act) and can achieve goals in a rich world with diverse language, bridging the gap between chit-chat and goal-oriented dialogue.