164,748 research outputs found
Cohen, Pamela and Leonard Trip to the U.S.S.R. (98 digital images)
No full textPhotographs within the folder were taken during Pamela B. Cohen's travels in the U.S.S.R. and during various events related to the American Soviet Jewry Movement.Digital ImageDigital finding aid
On the local-indicability cohen–lyndon theorem
No full textFor a group H and a subset X of H, we let HX denote the set {hxh?1 | h ? H, x ? X}, and when X is a free-generating set of H, we say that the set HX is a Whitehead subset of H. For a group F and an element r of F, we say that r is Cohen–Lyndon aspherical in F if F{r} is a Whitehead subset of the subgroup of F that is generated by F{r}. In 1963, Cohen and Lyndon (D. E. Cohen and R. C. Lyndon, Free bases for normal subgroups of free groups, Trans. Amer. Math. Soc. 108 (1963), 526–537) independently showed that in each free group each non-trivial element is Cohen–Lyndon aspherical. Their proof used the celebrated induction method devised by Magnus in 1930 to study one-relator groups. In 1987, Edjvet and Howie (M. Edjvet and J. Howie, A Cohen–Lyndon theorem for free products of locally indicable groups, J. Pure Appl. Algebra 45 (1987), 41–44) showed that if A and B are locally indicable groups, then each cyclically reduced element of A*B that does not lie in A ? B is Cohen–Lyndon aspherical in A*B. Their proof used the original Cohen–Lyndon theorem. Using Bass–Serre theory, the original Cohen–Lyndon theorem and the Edjvet–Howie theorem, one can deduce the local-indicability Cohen–Lyndon theorem: if F is a locally indicable group and T is an F-tree with trivial edge stabilisers, then each element of F that fixes no vertex of T is Cohen–Lyndon aspherical in F. Conversely, by Bass–Serre theory, the original Cohen–Lyndon theorem and the Edjvet–Howie theorem are immediate consequences of the local-indicability Cohen–Lyndon theorem. In this paper we give a detailed review of a Bass–Serre theoretical form of Howie induction and arrange the arguments of Edjvet and Howie into a Howie-inductive proof of the local-indicability Cohen–Lyndon theorem that uses neither Magnus induction nor the original Cohen–Lyndon theorem. We conclude with a review of some standard applications of Cohen–Lyndon asphericit
Audiocassette: "Gorodetsky Signatures 19/09/84; Pam Cohen-Usoskin" : Pamela B. Cohen Papers (P-897) box 46 tape 61
No full textThe recordings found in this collection contain notes, opinions, statements and allegations that may or may not be substantiated. American Jewish Historical Society and the Center for Jewish History do not represent or endorse the accuracy or reliability of any findings, conclusions, recommendations, opinions or statements expressed in the recordings.Digital recordingRussianDigital finding aid available
The Saul B. Cohen Papers
No full textSaul B. Cohen was a Professor of Geography and Director of the Graduate School of Geography from 1965 to 1979. The papers reflect the wide range of his activities during that time. They provide information about his leadership of the Graduate School of Geography and Clark University affairs. Also discussed are his scholarship, participation in the American Geographical Society and the Association of American Geographers, and contributions to programs to improve geographical instruction
Audiocassette: "Volvovsky" : Pamela B. Cohen Papers (P-897) box 46 tape 38
No full textThe recordings found in this collection contain notes, opinions, statements and allegations that may or may not be substantiated. American Jewish Historical Society and the Center for Jewish History do not represent or endorse the accuracy or reliability of any findings, conclusions, recommendations, opinions or statements expressed in the recordings.Digital recordingRussianDigital finding aid available
Audiocassette: "Leningrad Appeal" : Pamela B. Cohen Papers (P-897) box 46 tape 51
No full textThe recordings found in this collection contain notes, opinions, statements and allegations that may or may not be substantiated. American Jewish Historical Society and the Center for Jewish History do not represent or endorse the accuracy or reliability of any findings, conclusions, recommendations, opinions or statements expressed in the recordings.Digital recordingRussianDigital finding aid available
Audiocassette: "Women to American Congress" : Pamela B. Cohen Papers (P-897) box 46 tape 71
No full textThe recordings found in this collection contain notes, opinions, statements and allegations that may or may not be substantiated. American Jewish Historical Society and the Center for Jewish History do not represent or endorse the accuracy or reliability of any findings, conclusions, recommendations, opinions or statements expressed in the recordings.Digital recordingRussianDigital finding aid available
Audiocassette: "Volvovksy": Pamela B. Cohen Papers (P-897) box 45 tape 32
No full textDigital recordingDigital finding aid available
Audiocassette: "Candidates Congress Nepomnishaya Letter" : Pamela B. Cohen Papers (P-897) box 46 tape 86
No full textThe recordings found in this collection contain notes, opinions, statements and allegations that may or may not be substantiated. American Jewish Historical Society and the Center for Jewish History do not represent or endorse the accuracy or reliability of any findings, conclusions, recommendations, opinions or statements expressed in the recordings.Digital recordingRussianDigital finding aid available
Microcassette: "Enid and Stuart Wurtman KGB" : Pamela B. Cohen Papers (P-897) box 46 microcassette 8
No full textThe recordings found in this collection contain notes, opinions, statements and allegations that may or may not be substantiated. American Jewish Historical Society and the Center for Jewish History do not represent or endorse the accuracy or reliability of any findings, conclusions, recommendations, opinions or statements expressed in the recordings.Digital recordingRussianDigital finding aid available
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