Science Focus (issue 26)

Since the main purpose of lacing a shoe is to pull the two sides of the shoe together, we can add a constraint that three consecutive eyelets along a lacing can’t all be in the same column [1]. In other words, we can’t form a long vertical line along a single column. “Dense” lacing methods have the extra condition that the lace always alternates between columns A and B; in other words, there are no vertical segments. The three most common dense methods are shown in Figure 2, which we’ll call the crisscross, the European, and the shoe-store methods [2]. 由於穿鞋帶的主要目的是把鞋的左右兩邊拉在一 起,因此我們可以加一條規則,訂明鞋帶不能連續穿 過三個或以上同一行的孔眼 [1],換言之即是我們不 能在同一行穿一條長直線。 「緊密」綁法還有多一個額外條件,就是鞋帶 必須在A、B行之間交錯,不能包含垂直線段。圖 二顯示三種最常見的緊密綁法,分別是交叉綁法 (crisscross)、歐洲綁法(European)和鞋店綁法 (shoe-store)[2]。 Figure 2 Common dense lacing methods: crisscross (left), European (middle), and shoe-store (right). 圖二 常見的緊密綁法:交叉綁法(左)、歐洲綁法(中)和 鞋店綁法(右) On the other hand, two common methods that use vertical segments are Canadian straitlacing and the bowtie methods (Figure 3). (Canadian straitlacing is named for its historical usage by Canada’s armed forces, mainly because boots laced this way can be easily removed with one cut of a knife in case of emergencies [3].) 另一方面,包含垂直線段的兩個常見綁法是加 拿大五線譜綁法(Canadian straitlacing)和領結 綁法(bowtie)(圖三)。(前者是傳統上加拿大軍 隊使用的綁法,優點是在危急時用一刀就能把軍靴 的鞋帶切開,容易把鞋脫出 [3]。) Figure 3 Common lacing methods which use vertical segments: Canadian straitlacing (left) and bowtie (right). Gray lines represent the segments that cannot be seen from outside. 圖三 包含垂直線段的常見綁法:加拿大五線譜綁 法(左)和領結綁法(右)。灰色線代表藏在底下的 鞋帶。