On (1 + ε)-Approximate (Vertex) Cut Sparsifiers

Explore a lecture on approximate cut sparsifiers in graph theory. Delve into the construction of high-quality cut sparsifiers for planar and quasi-bipartite graphs. Learn about new results showing planar graphs admit planar quality-(1+ε) cut sparsifiers of size Õ(k/poly(ε)), contrasting with the 2^Ω(k) lower bound for quality-1 cases. Discover how quasi-bipartite graphs allow quality-1 cut sparsifiers of size k^O(k^2), improving on general graph bounds. Examine the limitations of contraction-based approaches for constructing optimal cut sparsifiers, particularly for quasi-bipartite graphs. Gain insights into graph compression techniques and their applications in sublinear graph simplification.