sub-types of radical feminism have emerged, such as cultural feminism, separatist feminism, trans-exclusionary radical feminism, and anti-pornography feminism, the last opposed by sex-positive feminism. Separatist and lesbian Separatist feminism is a form of radical feminism that does not support heterosexual relationships. Lesbian feminism is thus closely related. Separatist feminism's proponents argue that the sexual disparities between men and women are unresolvable. Separatist feminists generally do not feel that men can make positive contributions to the feminist movement and that even well-intentioned men replicate patriarchal dynamics. Author Marilyn Frye describes separatist feminism as "separation of various sorts or modes from men and from institutions, relationships, roles and activities that are male-defined, male-dominated, and operating for the benefit of males and the maintenance of male privilege—this separation being initiated or maintained, at will, by women". Socialist and Marxist Socialist feminism connects the oppression of women to Marxist ideas about exploitation, oppression and labor. Socialist feminists think unequal standing in both the workplace and the domestic sphere holds women down. Socialist feminists see prostitution, domestic work, childcare, and marriage as ways in which women are exploited by a patriarchal system that devalues women and the substantial work they do. Socialist feminists focus their energies on far-reaching change that affects society as a whole, rather than on an individual basis. They see the need to work alongside not just men but all other groups, as they see the oppression of women as a part of a larger pattern that affects everyone involved in the capitalist system. Marx felt that when class oppression was overcome, gender oppression would vanish as well; this is Marxist feminism. Some socialist feminists, many of Radical Women and the Freedom Socialist Party, point to the classic Marxist writings of Frederick Engels and August Bebel as a powerful explanation of the link between gender oppression and class exploitation. To some other socialist feminists, this view of gender oppression is naive and much of the work of socialist feminists has gone towards separating gender phenomena from class phenomena. Some contributors to socialist feminism have criticized these traditional Marxist ideas for being largely silent on gender oppression except to subsume it underneath broader class oppression. In the late nineteenth century and early twentieth century, both Clara Zetkin and Eleanor Marx were against the demonization of men and supported a proletarian revolution that would overcome as many male–female inequalities as possible. most Marxist leaders,