Admissible extremal rays and the anticanonical minimal model program
Abstract
We develop an anticanonical minimal model program for projective ℚ-factorial klt pairs (X,Δ) such that −(KX+Δ) is pseudoeffective. We first prove the cone and contraction theorems for potentially klt triples and establish the existence of flips for such triples. Using these results, we introduce the notion of admissible extremal rays and show that (KX+Δ)-positive admissible extremal rays are precisely the rays that are to be contracted by −(KX+Δ)-MMP. The elementary MMP steps associated to such admissible rays preserve klt singularities. For potentially klt pairs (X,Δ) with ℚ-divisors Δ, we prove that every (KX+Δ)-positive extremal ray is admissible and obtain a cone theorem for the (KX+Δ)-positive part of the Mori cone. Assuming termination of the anticanonical minimal model program, we establish a dichotomy: potentially klt pairs admit anticanonical minimal models, whereas non-potentially klt pairs admit non-admissible models.
Related
- Computation of Free Boundary Minimal Tori via Extremal Steklov Eigenvalues
- Compact Kähler surfaces with semipositive anticanonical bundle
- Automorphism groups and Homogeneous fibrations on projective varieties with nef anticanonical divisors
- Kawamata--Miyaoka type inequality for varieties with nef anticanonical divisor
- Sharp Quadratic Bounds for Anticanonical Volumes of Weak Fano Surfaces
BibTeX
@misc{choi2026admissible,
title = {{Admissible extremal rays and the anticanonical minimal model program}},
author = {Sung Rak Choi and Sungwook Jang and Dae-Won Lee},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.04145},
eprint = {2611.04145},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.04145},
}
RIS
TY - UNPB
TI - Admissible extremal rays and the anticanonical minimal model program
AU - Sung Rak Choi
AU - Sungwook Jang
AU - Dae-Won Lee
PY - 2026
DA - 2026/11/03
PB - arXiv
DO - 10.48550/arxiv.2611.04145
UR - https://arxiv.org/abs/2611.04145
AB - We develop an anticanonical minimal model program for projective ℚ-factorial klt pairs (X,Δ) such that −(K_X+Δ) is pseudoeffective. We first prove the cone and contraction theorems for potentially klt triples and establish the existence of flips for such triples. Using these results, we introduce the notion of admissible extremal rays and show that (K_X+Δ)-positive admissible extremal rays are precisely the rays that are to be contracted by −(K_X+Δ)-MMP. The elementary MMP steps associated to such admissible rays preserve klt singularities. For potentially klt pairs (X,Δ) with ℚ-divisors Δ, we prove that every (K_X+Δ)-positive extremal ray is admissible and obtain a cone theorem for the (K_X+Δ)-positive part of the Mori cone. Assuming termination of the anticanonical minimal model program, we establish a dichotomy: potentially klt pairs admit anticanonical minimal models, whereas non-potentially klt pairs admit non-admissible models.
ER -