Keynote Papers.- Data Spaces: Combining Goal-driven and Data-driven Approaches in Community Decision Sand Negotiation Support.- The strange absence of abstraction levels in designing HCI.- General Topics in Group Decision and Negotiation.- Stream Introduction: General Topics in Group Decision and Negotiation.- A framework for collaborative disaster response: A grounded theory approach.- Convergent Menus of Social Choice Rules.- Fuzzy group decision-making for the remediation of uranium mill tailings.- Conflict Resolution.- Stream Introduction: Conflict Resolution.- Evolutional Analysis for the South China Sea Dispute based on the Two-stage Attitude of Philippines.- Emotions in Group Decision and Negotiation.- Stream Introduction: Emotions in Group Decision and Negotiation.- Effects of Pre-Negotiation Behavior on the Subsequent Episode.- Negotiation Support Systems and Studies.- Stream Introduction: Negotiation Support Systems and Studies.- A Lifecycle Macro Phase Model for Negotiation.- Decision Problems in Requirements Negotiations - Identifying the Underlying Structures.- The Role of Sentiment and Cultural Differences in the Communication Process of e-Negotiations.- Nucleolus-based compensation payments for automated negotiations of complex contracts.- Preference Modelling for Group Decision and Negotiation.- Stream Introduction: Preference Modeling for Group Decision and Negotiation.- Choosing a Voting Procedure for the GDSS GRUS.- Building a shared model for multi-criteria group decision making: Experience from a case study for sustainable transportation planning in Quebec City.- A group decision outranking approach for the agricultural technology packages selection problem.- Can the holistic preference elicitation be used to determine the accurate negotiation offer scoring systems? A comparison of direct rating and UTASTAR technique.- The heuristics and biases in using the negotiation support systems.