We find constrained instantons in Einstein gravity with and without a cosmological constant. These configurations are not saddle points of the Einstein-Hilbert action, yet they contribute to non-perturbative processes quantum gravity. In some cases we expect that give dominant contribution from spacetimes certain fixed topologies. With negative constant, these metrics describe wormholes connect...

The minimum-cost arborescence problem is a well-studied in the area of graph theory, with known polynomial-time algorithms for solving it. Previous literature introduced new variations on original different objective function and/or constraints. Recently, Precedence-Constrained Minimum-Cost Arborescence was proposed, which precedence constraints are enforced pairs vertices. These prevent format...

We develop a non-negative polynomial minimum-norm likelihood ratio (PLR) of two distributions which only moments are known. The PLR converges to the true, unknown, ratio. show consistency, obtain asymptotic distribution for coefficients estimated with sample moments, and present applications. first develops unknown transition density jump-diffusion process. second modifies Hansen-Jagannathan pr...

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The paper presents a study in which participants learned computer literacy by having a spoken conversation with AutoTutor, an intelligent tutoring system with conversational dialogue. Thirty students completed a multiple-choice pre-test, a 35-minute training session, and a multiple-choice post-test. After completing the post-test, students reviewed their tutorial interaction and judged what emo...