COMPUTATIONAL PROBLEMS IN ABSTRACT ALGEBRA.

COMPUTATIONAL PROBLEMS IN ABSTRACT ALGEBRA. COMPUTATIONAL PROBLEMS IN ABSTRACT ALGEBRA.

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166 Marshall Hall Jr. Since t moves all letters it must interchange the orbits of odd length. In particular if t = (03, Ai) then Ai is one of the numbers 51,. . . ,57,65,. . , ,71, 72,. . ., 78. As tat = a-l, where(-,Ai,-,Ai...) (02,03,04,05,06,07,08) (6.15) (-, Ai, -, Ai, . . . . . . . a) is in some order (51, 57, 56, 55, 54, 53, 52), (65,71,70,69,68,67,66) or (72,78,77,76,75,74,73) and also b2dl = zi . 0 i We have b2a4 = (OO)(Ol, 13, 35,26,04, 24, 15, 30)(02, 20,21, 14) (03, 10, 18, 19, 33, 05, 11, 32)(06, 36, 16, 17) (07, 23, 34, 22,09,27,08, 25)( 12, 31, 29,28) (37, 41, 60, 88, 56, 53, 90, 61)(38, 71, 66, 40, 44, 62, 59, 50) (39, 79)(42, 57, 73, 78, 52,43,45,49)(46, 51, 48,93, 84, 89, 81, 99) (47, 72)(54, 65, 55, 85, 67, 96, 70, 80)(58, 69, 77, 86, 83, 98, 95, 75) (63,76,97, 94, 82, 92, 74, 68)(64)(87,91) (6.16) Here Ai = 73, Aj = 78 is the only pair from the 21 orbit of (a, d) in Ai the 63 orbit of H satisfying b2d = 0 A. and a-l = (. . . Ai,-,Aj. . .). Hence from (6.13) we must have t = (03,‘73). The equation (6.13) and the relations tat = a-l, tc = ct now completely determine t: t = (00,01)(02, 74)(03, 73)(04, 72)(05, 78)(06, 77)(07, 76)(08, 75)(09, 34) (10, 33)(11, 32)(12, 31)(13, 30)(14, 36)(15, 35)(16, 71)(17,70)(18, 69) (19, 68)(20, 67)(21, 66)(22, 65)(23, 53)(24, 52)(25, 51)(26, 57)(27, 56) (28, 55)(29, 54)(37,91)(38, 90)(39, 89)(40, 88)(41, 87)(42, 86)(43, 92) (44,99)(45,98)(46,97)(47,96)(48,95)(49,94)(50,93)(58, 85)(59, 84) (6.17) (60, 83)(61, 82)(62, 81)(63, 80)(64, 79). We now have a permutation group G on 100 letters 00, 01,. . . ,99, G = (a, b, an t) d a group H = (a, b) fixing 00 where it is known that H is the simple group of order 6048. Let M = Gee be the subgroup of G fixing 00. It is well known that M is generated by the 300 elements xia Xp-“, xtb z-l, xit Xif-ly (6.18) , i=OO,..., 99, are coset representatives of M in G and 7 = xj is the coset representative of My = MXj. Here, with the help Simple groups of order less than one million 167 of Mr. Peter Swinnerton-Dyer and the Titan computer at the Cambridge University Mathematical Laboratory, it was shown that each of the 300 permutations in (6.18) lies in H = (a, b). Thus M C H, and so M = H, whence Goo = H and G is of order 604,800. It remains to be shown that G is simple. In G the normafizer of the group (a) contains the element t interchanging 00 and 01. As these are the only letters fixed by (a) it follows that [N&(a))] = 2. As INH((a))I = 21 it follows that IN&(a))/ = 42 and (a) = S(7) is its own centralizer in G. In a chief series for G one of the factors has order a multiple of 6048. If this is not a minimal normal subgroup, then a minimal normal subgroup K has order 2, 4, 5, or 25. But then an S(7) normalizing K must also centralize K, which is false since S(7) is its own centralizer. Hence a minimal normal subgroup K has order a multiple of 6048 and also 14,400 since it must contain all 14,400 S(7)‘s. Thus either [GX] = 2 or G = K and G is simple. If [G:K] = 2 then N,(7) is of order 21 and so tcj K but HE K. But mapping G/K onto the group + 1, - 1 we map H- + 1, t - - 1 and this conflicts with the relation (6.12). Hence G is simple. As this is written some questions remain unanswered. The original character table given by Janko has been shown by Walter Feit to be in error. Janko has made corrections to his table. The character table of the group constructed here has not yet been calculated. And it has not been established that there is a unique simple group or order 604,800. [Added in proof by the Editor: The uniqueness of the simple group of order 604,800 has since been established ; see Marshall Hall Jr. and David Wales: The simple group of order 604 800, J. Algebra 9 (1968), 417-450.] REFERENCES 1. E. ARTTN: Geometric Algebra (Interscience, New York, 1957). 2. R. BRAUER: Investigations on group characters. Ann. of Math. 42 (1941), 936-958. 3. R. BRAUER: On groups whose order contains a prime number to the first power, part I, Am. J. Math. 64 (1942), 401-420; part II, Am. J. Math. 64 (1942), 421-440. 4. R. BRAUER: On the connections between the ordinary and the modular characters of groups of finite order. Ann. of Math. 42 (1941). 926-935. 5. R. BRAIJER: On permutation groups of prime’degree and related classes of groups. Ann. of Math. 44 (1943), 57-79. 6. R. BRAUER: Zur Darstellungstheorie der Gruppen endlicher Ordnung, part I, Math. Zeit. 63 (1956), 406444; part II, Math. Zeit. 72 (1959), 25-46. 7. R. BRAUER: Some applications of the theory of blocks of characters of finite groups, J. of Algebra, part I, 1(1964), 152-167; part II, 1(1964), 307-334; part III, 3 (1966), 225-255. 8. R. BRAUER and K. A. FOWLER: On groups of even order. Ann. of Math. 62 (1955), 5655.583. 9. R. BRAUER and C. NESBITT: On the modular characters of groups. Ann. of Math. 42 (1941), 556-590. 10. R. BRAUER and W. F. REYNOLDS: On a problem of E. Artin. Ann. of Math. 68 (1958). 713-720. CPA 12

168 Marshall Hall Jr. 11. R. BRAUER and M. SUZUKI: On finite groups of even order whose 2-Sylow group is a quatemion group. Proc. Nat. Acad. Sci. U.S.A. 45 (1959), 1757-1759. 12. R. BRAUER and H. F. TUAN: On simple groups of finite order. Bull. Amer. Math. Sot. 51 (1945), 756-766. 13. J. S. BRODKEY: A note on finite groups with an Abelian Sylow group. Proc. Amer. Math. Sot. 14 (1963), 132-133. 14. W. BURNSIDE: The Theory of Groups, 2nd edition (Cambridge University Press, 1911). 15. C. CIIEVALLEY: Sur certains groupes simples. Tdhoku Math. J. (2) 7 (1955), 14-66. 16. EVERJXT C. DADE: Blocks with cyclic defect groups. Ann. of Math. 84 (1966), 20-48. 17. L. E. DICKSON: Linear Groups (Reprinted by Dover, New York, 1958). 18. WALTER FEIT: On finite linear groups. J. of Algebra 5 (1967). 378-400. 19. ‘W. FEIT and JOHN THOMPSON: Solvability of groups of odd order. Pacific J. Math. 13 (1963), 775-1029. 20. W. FErrand JOHN THOMPSON: Groups which have a faithful representation of degree less than (p- 1)/2. Pacific J. Math. 11 (1961), 1257-1262. 21. D. GORENSTEIN: Finite groups in which Sylow 2-subgroups are Abelian and centralizers of involutions are solvable. Canad. J. Math. 17 (1965). 860-906. 22. D. GORENSTEIN and J. H. WALTER: The characterization of finite groups with dihedral Sylow 2-subgroups. J. of Algebra, part I, 2 (1965), 85-151; part II, 2 (1965), 218-270; part III, 2 (1965), 354-393. 23. MARSHALL HALL JR. : The Theory of Groups (Macmillan, New York, 1959). 24. MARSHALL HALL JR. : On the number of Sylow subgroups in a finite group, to appear in J. of Algebra. 25. ZVONOMIR JANKO: A new finite simple group with Abelian Sylow 2-subgroups and its characterization. J. of Algebra 3 (1966), 147-186. 26. E. L. MICHAELS: A study of simple groups of even order. Ph.D. Thesis, Notre Dame University, 1963. 27. -AK REE: A family of simple groups associated with the simple Lie algebra of type (Ga. Amer. J. Math. 83 (1961), 432-462. 28. RIMHAK REE: A family of simple groups associated with the simple Lie algebra of type (F,). Amer. J. Math. 83 (1961). 401-431. 29. &AI &&JR: ‘iSber eine Klasse von endlichen Gruppen linearer Substitutionen. Sitz. der Preussischen Akad. Berlin (1905), 77-91. 30. R. G. STANTON: The Mathieu groups. Canad. J. Math. 3 (1951), 164-174. 31. MICHIO SUZUKI: A new type of simple groups of finite order. Proc. Nat. Acad. Sci. U.S.A. 46 (1960), 868-870. 32. JOHN G. THOMPSON: Normalp-complements for finite groups. J. of Algebra 1 (1964), 43-46. 33. JOHN G. THOMPSON: N-groups. To be published. 34. HSIO F. TUAN: On groups whose orders contain a prime number to the first power. Ann. of Math. 45 (1944), 110-140. Computational methods in the study of permutation groups’ CHARLES C. SIMS 1. Introduction. One of the oldest problems in the theory of permutation groups is the determination of the primitive groups of a given degree. During a period of several decades a great deal of effort was spent on constructing the permutation groups of low degree. For degrees 2 through 11 lists of all permutation groups appeared. For degrees 12 through 15 the lists were limited to the transitive groups, while only the primitive groups of degrees 16 through 20 were determined. A detailed account of the early work in this area can be found in the first article of [12] and references to later papers are given in [1] and in [2] p. 564. The only recent work of this type known to the author is that of Parker, Nikolai, and Appel [13], [14], and a series of papers by Ito. These authors have shown that for certain prime degrees any non-solvable transitive group contains the alternating group. The basic assumption of this paper is that it would be useful to extend the determination of the primitive groups of low degree and that with recent advances in group theory and the availability of electronic computers for routine calculations it is feasible to carry out the determination as far as degree 30 and probably farther. Ideally one would wish to have an algorithm sufficiently mechanical and efficient to be carried out entirely on a computer. Such an algorithm does not yet exist. The procedure outlined in this paper combines the use of a computer with more conventional techniques. Suppose we wish to find the primitive groups of a given degree n. It will be assumed that the primitive groups of degree less than n have already been determined. Since a minimal normal subgroup of a primitive group is transitive and is a direct product of isomorphic simple groups, the first step is to take each of the known simple groups H, including the groups of prime order, determine the transitive groups M of degree IZ isomorphic to the direct product of one or more copies of H, and then for each such group M find the primitive groups containing M as a normal subgroup. While this is by no means a trivial procedure, it is considerably 12' t This research was supported in part by the National Science Foundation. 169

168 Marshall Hall Jr.<br />

11. R. BRAUER and M. SUZUKI: On finite groups of even order whose 2-Sylow group is a<br />

quatemion group. Proc. Nat. Acad. Sci. U.S.A. 45 (1959), 1757-1759.<br />

12. R. BRAUER and H. F. TUAN: On simple groups of finite order. Bull. Amer. Math.<br />

Sot. 51 (1945), 756-766.<br />

13. J. S. BRODKEY: A note on finite groups with an Abelian Sylow group. Proc. Amer.<br />

Math. Sot. 14 (1963), 132-133.<br />

14. W. BURNSIDE: The Theory of Groups, 2nd edition (Cambridge University Press,<br />

1911).<br />

15. C. CIIEVALLEY: Sur certains groupes simples. Tdhoku Math. J. (2) 7 (1955), 14-66.<br />

16. EVERJXT C. DADE: Blocks with cyclic defect groups. Ann. of Math. 84 (1966), 20-48.<br />

17. L. E. DICKSON: Linear Groups (Reprinted by Dover, New York, 1958).<br />

18. WALTER FEIT: On finite linear groups. J. of Algebra 5 (1967). 378-400.<br />

19. ‘W. FEIT and JOHN THOMPSON: Solvability of groups of odd order. Pacific J. Math.<br />

13 (1963), 775-1029.<br />

20. W. FErrand JOHN THOMPSON: Groups which have a faithful representation of degree<br />

less than (p- 1)/2. Pacific J. Math. 11 (1961), 1257-1262.<br />

21. D. GORENSTE<strong>IN</strong>: Finite groups in which Sylow 2-subgroups are Abelian and centralizers<br />

of involutions are solvable. Canad. J. Math. 17 (1965). 860-906.<br />

22. D. GORENSTE<strong>IN</strong> and J. H. WALTER: The characterization of finite groups with dihedral<br />

Sylow 2-subgroups. J. of Algebra, part I, 2 (1965), 85-151; part II, 2 (1965),<br />

218-270; part III, 2 (1965), 354-393.<br />

23. MARSHALL HALL JR. : The Theory of Groups (Macmillan, New York, 1959).<br />

24. MARSHALL HALL JR. : On the number of Sylow subgroups in a finite group, to appear<br />

in J. of Algebra.<br />

25. ZVONOMIR JANKO: A new finite simple group with Abelian Sylow 2-subgroups and its<br />

characterization. J. of Algebra 3 (1966), 147-186.<br />

26. E. L. MICHAELS: A study of simple groups of even order. Ph.D. Thesis, Notre<br />

Dame University, 1963.<br />

27. -AK REE: A family of simple groups associated with the simple Lie algebra of<br />

type (Ga. Amer. J. Math. 83 (1961), 432-462.<br />

28. RIMHAK REE: A family of simple groups associated with the simple Lie algebra of<br />

type (F,). Amer. J. Math. 83 (1961). 401-431.<br />

29. &AI &&JR: ‘iSber eine Klasse von endlichen Gruppen linearer Substitutionen.<br />

Sitz. der Preussischen Akad. Berlin (1905), 77-91.<br />

30. R. G. STANTON: The Mathieu groups. Canad. J. Math. 3 (1951), 164-174.<br />

31. MICHIO SUZUKI: A new type of simple groups of finite order. Proc. Nat. Acad. Sci.<br />

U.S.A. 46 (1960), 868-870.<br />

32. JOHN G. THOMPSON: Normalp-complements for finite groups. J. of Algebra 1 (1964),<br />

43-46.<br />

33. JOHN G. THOMPSON: N-groups. To be published.<br />

34. HSIO F. TUAN: On groups whose orders contain a prime number to the first power.<br />

Ann. of Math. 45 (1944), 110-140.<br />

Computational methods in the study<br />

of permutation groups’<br />

CHARLES C. SIMS<br />

1. Introduction. One of the oldest problems in the theory of permutation<br />

groups is the determination of the primitive groups of a given degree.<br />

During a period of several decades a great deal of effort was spent on<br />

constructing the permutation groups of low degree. For degrees 2 through<br />

11 lists of all permutation groups appeared. For degrees 12 through 15<br />

the lists were limited to the transitive groups, while only the primitive<br />

groups of degrees 16 through 20 were determined. A detailed account of<br />

the early work in this area can be found in the first article of [12] and references<br />

to later papers are given in [1] and in [2] p. 564. The only recent<br />

work of this type known to the author is that of Parker, Nikolai, and Appel<br />

[13], [14], and a series of papers by Ito. These authors have shown that<br />

for certain prime degrees any non-solvable transitive group contains the<br />

alternating group.<br />

The basic assumption of this paper is that it would be useful to extend<br />

the determination of the primitive groups of low degree and that with<br />

recent advances in group theory and the availability of electronic computers<br />

for routine calculations it is feasible to carry out the determination<br />

as far as degree 30 and probably farther. Ideally one would wish to have<br />

an algorithm sufficiently mechanical and efficient to be carried out entirely<br />

on a computer. Such an algorithm does not yet exist. The procedure outlined<br />

in this paper combines the use of a computer with more conventional<br />

techniques.<br />

Suppose we wish to find the primitive groups of a given degree n. It<br />

will be assumed that the primitive groups of degree less than n have already<br />

been determined. Since a minimal normal subgroup of a primitive<br />

group is transitive and is a direct product of isomorphic simple groups, the<br />

first step is to take each of the known simple groups H, including the groups<br />

of prime order, determine the transitive groups M of degree IZ isomorphic<br />

to the direct product of one or more copies of H, and then for each<br />

such group M find the primitive groups containing M as a normal subgroup.<br />

While this is by no means a trivial procedure, it is considerably<br />

12'<br />

t This research was supported in part by the National Science Foundation.<br />

169

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