You are a proptech entrepreneur specializing in vacation rentals. Design a startup concept called 'RentalBrain' that uses AI to optimize pricing, automate guest communication, and manage short-term rentals across multiple platforms. The concept must include: 1) Market opportunity: growth of short-term rentals, Airbnb/Vrbo hosts, 2) Problem statement: managing multiple listings across platforms is time-consuming, 3) Solution overview: AI platform that centralizes management and optimizes pricing dynamically, 4) Core features: dynamic pricing algorithms, automated messaging, channel management, guest screening, calendar sync, 5) AI capabilities: demand forecasting, competitor analysis, seasonal pricing recommendations, 6) Target customers: individual hosts, property managers, small rental businesses, 7) Business model: percentage of booking revenue, monthly subscription, 8) Technology: API integrations with booking platforms, machine learning models, mobile apps, 9) Partnerships: property management software, cleaning services, smart home device manufacturers, 10) Go-to-market: host communities, online forums, partnerships with vacation rental conferences.