Products of boundary classes on (M)over-bar0,n via balanced weights

In this note, we give a simple closed formula for an arbitrary product, landing in dimension 0, of boundary classes on the Deligne-Mumford moduli space (M) over bar (0,n). For any such boundary strata X-T1 , ... , X-Tl, we show the intersection product integral Pi(l)(i=1)[X-Ti] is either a signed product of multinomial coefficients, or zero, and provide a simple criterion for determining when it is nonzero. We do not claim originality for our product formula, but to our knowledge it does not appear elsewhere in the literature. (c) 2024 Elsevier GmbH. All rights are reserved, including those for text and data mining, AI training, and similar technologies.