1. Contrast: Boolean operators are often expressed by contrast in Tang and Song poems, such as "But if you go up a storey, you will broaden your horizons by three hundred miles" (Du Fu's "Climbing the Mountain"), which means that "going up a storey" is a necessary condition for "being thousands of miles away". Only when you go up a storey, can you see the scenery farther away.
2. Hypothetical relationship: There are also many expressions of hypothetical relationship in Tang and Song poetry, such as "The apes on both sides of the strait can't stop crying, and the canoe has passed Chung Shan Man" (Li Bai's "Early Sending to Baidicheng"), which means that if the canoe has passed Chung Shan Man, then the apes on both sides of the strait will keep crying.
3. Coordinate relationship: In Tang and Song poetry, coordinate relationship can also be used to express Boolean operators, such as "Mountain blocks the daytime, and the sea discharges the golden river" (Wang Zhihuan's "In the Lodge of Herons"), which means that "Mountain blocks the daytime" and "Sea discharges the golden river" are two simultaneous actions.
4. Conditional relations: Conditional relations can also be used to express Boolean operators in Tang and Song poems, such as "The wild trail is dark and the river boat is bright" (Du Fu's "One Night in a Foreign Country"), which means that if the clouds on the wild trail are dark, the lights on the river boat will be particularly bright.
Generally speaking, the expression of Boolean operators in Tang and Song poetry is very flexible, and different expressions can be adopted according to different contexts and needs. These expressions can not only increase the artistry and expressiveness of poetry, but also provide readers with deeper thoughts and feelings.