设[tex=0.929x1.286]uswT/CEcOIwMpCvTz/zeaA==[/tex]是一个集合，则X的子集族[tex=0.714x1.286]iwb4zdN/wKhY8nxsKHlalg==[/tex]和[tex=0.571x1.286]P1K0SyhyzswPER3MAMCDsQ==[/tex]是[tex=0.929x1.286]uswT/CEcOIwMpCvTz/zeaA==[/tex]的同一个拓扑的两个基的充分必要条件是[tex=0.714x1.286]iwb4zdN/wKhY8nxsKHlalg==[/tex]和[tex=0.571x1.286]P1K0SyhyzswPER3MAMCDsQ==[/tex]满足条件：(l)如果[tex=4.429x1.286]k4xQq3GIG4C3q4lvqp7Q8KEnGDWVRAnax+hHoUwWSAY=[/tex]，则存在[tex=2.5x1.286]6oLbv7TqkjblFQgcdcD+/GoHUcNsJ0XBcZRpQmcA324=[/tex]使得[tex=4.5x1.286]pwQ/H6t8ilSOoEIQ2PbnR6da99/IPaq0/RK9hMunFgY=[/tex]；(2)如果[tex=4.286x1.286]R/H8+mImXaluNznGSw6aZtlHi+QtQVOLuosBGQyqQbA=[/tex]，则存在[tex=2.714x1.286]gSWgn/O9damfainlywoRuVmTmByluu0LRzw3Uti5feY=[/tex]使得[tex=4.5x1.286]ag+CI+Skvb0rpZQUjgApUiuAObz/egM70S3B7g/cM0w=[/tex]。