Abstract Placing D3-branes at conical Calabi-Yau threefold singularities produces many AdS5/CFT4 duals. Recent progress in differential geometry has produced a technique (called K-stability) to recognize which singularities admit conical Calabi-Yau metrics. On the other hand. the algebraic technique of non-commutative crepant resolutions. https://www.freaknleather.com/product-category/tube-notcher/