Definition: The input is taken from a negotiation between two participants who take the role of campsite neighbors and negotiate for Food, Water, and Firewood packages, based on their individual preferences and requirements. Given an utterance and recent dialogue context containing past 3 utterances (wherever available), output Yes if the utterance contains the vouch-fair strategy, otherwise output No. vouch-fair is a selfish negotiation strategy. It is used to call out fairness for personal benefit, either when acknowledging a fair deal or when the opponent offers a deal that benefits them. This can be through an explicit call out or can be implied.
Input: Context: 'Okay I think this might be a good deal. ' 'Actually, I've just thought about it and I'd also like one package of water. I think it'd be fair being that you're getting 2 packages of food.' 'Which means? Did you mean that I would take 2 packages of food and 2 packages of water? Then I will ask for one package of fire wood.'
Utterance: 'Being that you're getting 2 of 3 of the item (food) that for me is the highest value, I think it's only fair that I get all 3 of the medium value items (firewood) and one of the low value item (water). That would give me 5 packages and you 4 packages, but 2 of 4 of your packages are the high value items.'

Yes