Adrien Deloro, Eric Jaligot
We consider groups of finite Morley rank with solvable local subgroups of even and mixed types. We also consider miscellaneous aspects of small groups of finite Morley rank of odd type.
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Actions of $\operatorname{Alt}(n)$ on groups of finite Morley rank without involutions
本文研究了有限 Morley 秩群上 $\operatorname{Alt}(n)$ 的忠实作用，证明了无对合时不可解群秩的下界 $n$，并推广到可解群，进而应用于通用传递性限制。
This paper contains a stronger version of a final identification theorem for the `generic' groups of finite Morley rank.
We prove a general dichotomy theorem for groups of finite Morley rank with solvable local subgroups and of Prüfer p-rank at least 2, leading either to some p-strong embedding, or to the Prüfer p-rank being exactly 2.
The paper contains versions of the Strong Embedding Theorem and the Uniqueness Subgroup Theorem for groups of finite Morley rank and odd type which are needed for the study of permutations actions and modules in the finite Morley rank category.
In this work, we give two characterisations of the general linear group as a group $G$ of finite Morley rank acting on an abelian connected group $V$ of finite Morley rank definably, faithfully and irreducibly. To be more precise, we prove that if the pseudoreflection rank of $G$ is equal to the Morley rank of $V$, then $V$ has a vector space structure over an algebraically closed field, $G\cong GL(V)$ and the action is the natural action. The same result holds also under the assumption of Prufer 2-rank of $G$ being equal to the Morley rank of $V$.
We classify a large class of small groups of finite Morley rank: $N_\circ^\circ$-groups which are the infinite analogues of Thompson's $N$-groups. More precisely, we constrain the $2$-structure of groups of finite Morley rank containing a definable, normal, non-soluble, $N_\circ^\circ$-subgroup.
We show that a non-algebraic simple group of finite Morley rank with a definable representation over a field has no involutions, and otherwise resembles a bad group. In particular, the modern form of the Cherlin-Zilber alebaricity conjecture hold for such groups.
Mock hyperbolic reflection spaces and Frobenius groups of finite Morley rank
该研究定义伪双曲反射空间概念，用于分析有限Morley秩的Frobenius群，得出相关群的分裂性结论与秩不等式推论。
By exploiting the geometry of involutions in $N_\circ^\circ$-groups of finite Morley rank, we show that any simple group of Morley rank $5$ is a bad group all of whose proper definable connected subgroups are nilpotent of rank at most $2$. The main result is then used to catalog the nonsoluble connected groups of Morley rank $5$.
We lay down the fundations of the theory of groups of finite Morley rank in which local subgroups are solvable and we proceed to the local analysis of these groups. We prove the main Uniqueness Theorem, analogous to the Bender method in finite group theory, and derive its corollaries. We also consider homogeneous cases as well as torsion.
We prove that if $G$ is a group of finite Morley rank which acts definably and generically sharply $n$-transitively on a connected abelian group $V$ of Morley rank $n$ with no involutions, then there is an algebraically closed field $F$ of characteristic $\ne 2$ such that $V$ has a structure of a vector space of dimension $n$ over $F$ and $G$ acts on $V$ as the group $\operatorname{GL}_n(F)$ in its natural action on $F^n$. This is the final pre-publication version of the paper: A. Berkman and A. Borovik, Groups of finite Morley rank with a generically sharply multiply transitive action, J. Alg…
Finite group actions on abelian groups of finite Morley rank
本文在有限 Morley 秩范畴内研究有限群对无限交换群的作用，为移除“尖锐性”假设及证明单代数群作用的线性猜想提供关键工具。
We show that any simple group of Morley rank 4 must be a bad group with no proper definable subgroups of rank larger than 1. We also give an application to groups acting on sets of Morley rank 2.
We revisit the geometry of involutions in groups of finite Morley rank. Our approach unifies and generalises numerous results, both old and recent, that have exploited this geometry; though in fact, we prove much more. We also conjecture that this path leads to a new identification theorem for $\operatorname{PGL}_2(\mathbb{K})$.
We examine Weyl groups of minimal connected simple groups of finite Morley rank of degenerate type. We show that they are cyclic, and lift isomorphically to subgroups of the ambient group.
In this paper we study the algebraic structure of $ω$-stable bilinear maps, arbitrary rings and nilpotent groups. We will also provide rather complete structure theorems for the above structures in the finite Morley rank case.
We prove that in a connected group of finite Morley rank the centralizers of decent tori are connected. We then apply this result to the analysis of minimal connected simple groups of finite Morley rank. Our applications include general covering properties by Borel subgroups, the description of Weyl groups and the analysis of toral automorphisms.
Here we analyze a proper 2-generated core in a minimal counter example to the Cherlin-Zilber Algebraicity Conjecture for simple groups of finite Morley rank. We ultimately show that such a group is strongly embedded and the ambiant group is minimal connected simple.
Bisoluble and Binilpotent Skew Braces of Finite Morley Rank
研究有限Morley秩的连通斜括号，证明其加法与乘法群的幂零性或可解性可推出括号本身的左幂零性或弱可解性。
We prove several results about groups of finite Morley rank without unipotent p-torsion: p-torsion always occurs inside tori, Sylow p-subgroups are conjugate, and p is not the minimal prime divisor of our approximation to the ``Weyl group.'' These results are quickly finding extensive applications within the classification project.
The Şiş Kebap Theorem: A Generic Identification Theorem for Groups of Finite Morley Rank
本文提出有限 Morley 秩“通用”群的最终识别定理的新版本，发展了已有研究成果，为 Hrushovski 计划中有限 Morley 秩无限单群的分类提供支持。
We prove that if the group of fixed points of a generic automorphism of a simple group of finite Morley rank is pseudofinite, then this group is an extension of a (twisted) Chevalley group over a pseudofinite field. On the way to obtain this result, we classify non-abelian definably simple pseudofinite groups of finite centralizer dimension (using the ideas of John S. Wilson).
We show that a minimal counter example to the Cherlin-Zilber Algebraicity Conjecture for simple groups of finite Morley rank has Prufer 2-rank at most two. This article covers the signalizer functor theory and identifies the groups of Lie rank at least three; leaving the uniqueness case analysis to previous articles. This result signifies the end of the general methods used to handle large groups; hereafter each individual group PSL$_2$, PSL$_3$, PSp$_4$, and G$_2$ will require its own identification theorem.
One of the central tools in the classification of simple algebraic groups is the distinction between semisimple subgroups and unipotent subgroups. It is not a priori clear how to make this distinction for torsion-free subgroups of a group of finite Morley rank. We exploit the ``graded'' notion of 0-unipotence to develop a Sylow theory for torsion-free subgroups of a solvable group of finite Morley rank. This Sylow theory provides a robust alternative to the usual theory of Carter subgroups, and will be used in the analysis of intersections of Borel subgroups in minimal simple groups.
We deal with two forms of the "uniqueness cases" in the classification of large simple $K^*$-groups of finite Morley rank of odd type, where large means the $m_2(G)$ at least three. This substantially extends results known for even larger groups having \Prufer 2-rank at least three, to cover the two groups $\PSp_4$ and $\G_2$. With an eye towards distant developments, we carry out this analysis for $L^*$-groups which is substantially broader than the $K^*$ setting.
We prove a Jordan decomposition theorem for minimal connected simple groups of finite Morley rank with non-trivial Weyl group. From this, we deduce a precise structural description of Borel subgroups of this family of simple groups. Along the way we prove a Tetrachotomy theorem that classifies minimal connected simple groups. Some of the techniques that we develop help us obtain a simpler proof of a theorem of Burdges, Cherlin and Jaligot.
We modify the Frecon-Jaligot construction of Carter subgroups to show that a degenerate type group has a Carter subgroup invariant under the Sylow 2-subgroup of a group of automorphisms; thus reducing the need to know that Carter subgroups are conjugate in degenerate type groups.
We investigate the configuration where a group of finite Morley rank acts definably and generically $m$-transitively on an elementary abelian $p$-group of Morley rank $n$, where $p$ is an odd prime, and $m\geqslant n$. We conclude that $m=n$, and the action is equivalent to the natural action of $\operatorname{GL}_n(F)$ on $F^n$ for some algebraically closed field $F$. This strengthens our earlier result in arXiv:1802.05222, and partially answers two problems posed in [9].
We show that a minimal nonalgebraic simple groups of finite Morley rank has Prufer rank at most 2, and eliminates tameness from Cherlin and Jaligot's past work on minimal simple groups. The argument given here begins with the strongly embedded minimal simple configuration of Borovik, Burdges and Nesin. The 0-unipotence machinery of Burdges's thesis is used to analyze configurations involving nonabelian intersections of Borel subgroups. The number theoretic punchline of Cherlin and Jaligot has been replaced with a new genericity argument.
Small groups of finite Morley rank with a supertight automorphism
本文研究具有有限莫利秩和 Prüfer 2-秩1的无限单群，在超紧自同构作用下固定点子群均为伪有限的条件下，证明该群同构于某特征不为2的代数闭域上的 PGL₂(K)。
We show that for a wide class of groups of finite Morley rank the presence of a split $BN$-pair of Tits rank $1$ forces the group to be of the form $\operatorname{PSL}_2$ and the $BN$-pair to be standard. Our approach is via the theory of Moufang sets. Specifically, we investigate infinite and so-called hereditarily proper Moufang sets of finite Morley rank in the case where the little projective group has no infinite elementary abelian $2$-subgroups and show that all such Moufang sets are standard (and thus associated to $\operatorname{PSL}_2(F)$ for $F$ an algebraically closed field of chara…
Jaligot's Lemma states that the Fitting subgroups of distinct Borel subgroups do not intersect in a tame minimal simple groups of finite Morley. Such a strong result appears hopeless without tameness. Here we use the 0-unipotence theory to build a toolkit for the analysis of nonabelian intersections of Borel subgroups. As a demonstration, we show that any connected nilpotent subgroup of an intersection of Borel subgroups, in a nontame minimal simple group, must actually be abelian.
The present survey aims at being a list of Conjectures and Problems in an area of model-theoretic algebra wide open for research, not a list of known results. To keep the text compact, it focuses on structures of finite Morley rank, although the same questions can be asked about other classes of objects, for example, groups definable in $ω$-stable and $o$-minimal theories. In many cases, answers are not known even in the classical category of algebraic groups over algebraically closed fields.
We classify irreducible actions of connected groups of finite Morley rank on abelian groups of Morley rank 3.
Primitive permutation groups of finite Morley rank and affine type
本文综述有限 Morley 秩连通群的可定义本原作用，重点讨论含正则交换正规子群的仿射型本原群及其核心理论地位。
There is a longstanding conjecture, due to Gregory Cherlin and Boris Zilber, that all simple groups of finite Morley rank are simple algebraic groups. One of the major theorems in the area is Borovik's trichotomy theorem. The "trichotomy" here is a case division of the minimal counterexamples within odd type, i.e. groups with a divisibble connected component of the Sylow 2-subgroup. We introduce a charateristic zero notion of unipotence which can be used to obtain a connected nilpotent signalizer functor from any sufficiently non-trivial solvable signalizer functor. This result plugs seamlessl…
In this paper we prove that any strongly embedded subgroup of a K*-group G of finite Morley rank and odd type that does not interpret any bad field is solvable if its Pruefer 2-rank is at least 2. If the normal 2-rank of G is at least 3 this has two important consequences: If G contains a non-solvable centraliser of an involution, then G does not contain any proper 2-generated core and centralisers of involutions have trivial cores.
We show that the only transitive and generically $4$-transitive action of a group of finite Morley rank on a set of Morley rank $2$ is the natural action of $\operatorname{PGL}_3$ on the projective plane.
We show that the geometry associated to certain non-split sharply 2-transitive groups does not contain a proper projective plane. For a sharply 2-transitive group of finite Morley rank we improve known rank inequalities for this geometry and conclude that a sharply 2-transitive group of Morley rank 6 must be of the form $K\rtimes K^*$ for some algebraically closed field $K$.
We prove a non-generosity theorem for proper cosets in groups of finite Morley rank and elaborate on the theory of Weyl groups in this context.
Groups Acting Generically Multiply Transitively on Solvable Groups
本文在有限 Morley 秩设定下，完成了群在可解群上泛多重传递作用的分类，证明此类作用等价于一般线性群在代数闭域向量空间上的自然作用，并推广了可定义本原群的分类。
Bounding the degree of generic sharp transitivity
本研究在L-群条件下证明了有限Morley秩泛型锐t-传递置换群的次数满足t≤r+2，推进了Borovik-Cherlin猜想，证明基于三个独立的群作用相关关键要素。
There is no sad group of Morley rank 2n + 1 with an abelian Borel subgroup of rank n. In particular, Fr{é}con's Theorem follows: There is no bad group of Morely rank 3.
In this paper we investigate commuting involution graphs in classical affine Weyl groups. Let $W$ be a classical Weyl group of rank $n$, with $\tilde W$ its corresponding affine Weyl group. Our main result is that if $X$ is a conjugacy class of involutions in $\tilde W$, then the commuting involution graph $\mathcal{C}(\tilde W, X)$ is either disconnected or has diameter at most $n+2$. This bound is known to hold for types $\tilde A_n$ and $\tilde C_n$, so the main work of this paper is to prove the theorem for types $\tilde B_n$ and $\tilde D_n$.
Primitive pseudo-finite permutation groups of finite SU-rank
本文研究了有限SU-秩的原始伪有限置换群，证明了该群的秩可由另一个对象的秩限制，类似于Borovik和Cherlin的定理。
We classify irreducible SL(2,K)-modules of low Morley rank (at most 4.rk(K)) as a first step towards a more general conjecture.
We study a model theoretic context (finite thorn rank, NIP, with finitely satisfiable generics) which is a common generalization of groups of finite Morley rank and definably compact groups in o-minimal structures. We show that assuming thorn rank 1, the group is abelian-by-finite, and assuming thorn rank 2 the group is solvable by finite. Also a field is algebraically closed.
The maximal rank of a string group generated by involutions for alternating groups
本文研究了由对合生成的字符串群（SGGI）的秩，确定了$n$次交错群上SGGI秩的上界，并证明了当$n\equiv 0,1,4\pmod 5$时该上界是紧的。
We study the sublattices of the rank $2^d$ Barnes-Wall lattices $\bw d$ which occur as fixed points of involutions. They have ranks $2^{d-1}$ (for dirty involutions) or $2^{d-1}\pm 2^{k-1}$ (for clean involutions), where $k$, the defect, is an integer at most $\frac d 2$. We discuss the involutions on $\bw d$ and determine the isometry groups of the fixed point sublattices for all involutions of defect 1. Transitivity results for the Bolt-Room-Wall group on isometry types of sublattices extend those in \cite{bwy}. Along the way, we classify the orbits of $AGL(d,2)$ on the Reed-Muller codes $RM…
Involutions in the affine Conway group
本文研究仿射Conway群的对合共轭类，证明其有9个此类类，其中一类是K3曲面Enriques对合类的类似物，用Borcherds方法计算相关双曲格正交群，发现诱导腔有无限多墙。
In 2008, Borovik and Cherlin posed the problem of showing that the degree of generic transitivity of an infinite permutation group of finite Morley rank $(X,G)$ is at most $n+2$ where $n$ is the Morley rank of $X$. Moreover, they conjectured that the bound is only achieved (assuming transitivity) by $\operatorname{PGL}_{n+1}(\mathbb{F})$ acting naturally on projective $n$-space. We solve the problem under the two additional hypotheses that (1) $(X,G)$ is $2$-transitive, and (2) $(X-\{x\},G_x)$ has a definable quotient equivalent to $(\mathbb{P}^{n-1}(\mathbb{F}),\operatorname{PGL}_{n}(\mathbb{…
We show that a minimal counter example to the Cherlin-Zilber Algebraicity Conjecture for simple groups of finite Morley rank has normal 2-rank at most two, which is a tameness free version of Borovik's original trichotomy theorem. This result serves as a bridge by showing that there are no groups found strictly between the generic and quasithin cases, i.e. between groups of Lie rank at least three, and groups of Lie rank one and two. Again this result depends upon previous work for the uniqueness case analysis.
On the model theory of the Farey graph
研究费马图的模型论，证明其为ω稳定且莫利等级为ω。
In the stable general linear group over an arbitrary field, we prove that every element with determinant $\pm 1$ is the product of three involutions, and of no less in general. We also obtain several results of the same flavor, with applications to decompositions of automorphisms of an infinite-dimensional vector space that are scalar multiples of finite-rank perturbations of the identity.
Involutions in Coxeter groups
本文以高阶奇图刻画任意Coxeter群中对合的共轭类数，给出统一界、极值情形及多类群的计算公式。
We describe an algorithm to identify a minimal set of "braid relations" which span and preserve all sets of involution words for twisted Coxeter systems of finite or affine type. We classify the cases in which adding the smallest possible set of "half-braid" relations to the ordinary braid relations produces a spanning set: in the untwisted case, this occurs for the Coxeter systems which are finite with rank two or type $A_n$, or affine with rank three or type $\tilde A_n$. These results generalize recent work of Hu and Zhang on the finite classical cases.
Triples of involutions in PGL(2,q) and their incidence geometries
本文研究 PGL(2,q) 中三个对合生成的群与对应点三元组的几何性质之间的关系，证明陪集几何为正则 hypertope 当且仅当点三元组构成强非自极三角形，从而完全刻画了秩 3 且自同构群为 PGL(2,q) 子群的 hypertope，并给出非线性图情形的存在性。
Interval Garside groups arising from involutions in finite reflection groups
研究有限反射群中对合产生的区间加赛德群，通过考克斯特群绝对序限制到特定格来识别研究，除$B_n$型外所得群同构于直角阿廷群，还探讨了有限复反射群相关情况。
Weak order on groups generated by involutions
本文研究了involution系统中的弱序结构，探讨了其作为完全meet-semilattice的条件，并讨论了相关性质及开放问题。
Length-generating functions for twisted involutions of Coxeter groups
本文证明了有限秩Coxeter系统中扭曲对合的长度生成函数为有理函数，推导了类似抛物子群生长级数的递推关系，并推广到封闭子集，为Lusztig的幂级数恒等式提供了新证明。
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