▁somewhat ▁" t amer " ▁by ▁writing ▁them ▁in ▁terms ▁of ▁the ▁( bounded ) ▁unit ary ▁operators ▁ ▁and ▁. ▁The ▁resulting ▁bra iding ▁relations ▁for ▁these ▁operators ▁are ▁the ▁so - called ▁W ey l ▁relations ▁ ▁. ▁▁ ▁These ▁relations ▁may ▁be ▁thought ▁of ▁as ▁an ▁exponent i ated ▁version ▁of ▁the ▁canonical ▁commut ation ▁relations ; ▁they ▁reflect ▁that ▁transl ations ▁in ▁position ▁and ▁transl ations ▁in ▁momentum ▁do ▁not ▁comm ute . ▁One ▁can ▁easily ▁reform ulate ▁the ▁W ey l ▁relations ▁in ▁terms ▁of ▁the ▁representations ▁of ▁the ▁He isen berg ▁group . ▁ ▁The ▁uniqu eness ▁of ▁the ▁canonical ▁commut ation ▁relations — in ▁the ▁form ▁of ▁the ▁W ey l ▁relations — is ▁then ▁guaranteed ▁by ▁the ▁Stone – von ▁Ne umann ▁theorem . ▁ ▁It ▁is ▁important ▁to ▁note ▁that ▁for ▁technical ▁reasons , ▁the ▁W ey l ▁relations ▁are ▁not ▁strictly ▁equivalent ▁to ▁the ▁canonical ▁commut ation ▁relation ▁. ▁If ▁ ▁and ▁ ▁were ▁bounded ▁operators , ▁then ▁a ▁special ▁case ▁of ▁the ▁Baker – C amp bell – H aus dor ff ▁formula ▁would ▁allow ▁one ▁to ▁" ex ponent iate " ▁the ▁canonical ▁commut ation ▁relations ▁to ▁the ▁W ey l ▁relations . ▁Since , ▁as ▁we ▁have ▁noted , ▁any ▁operators ▁satisfying ▁the ▁canonical ▁commut ation ▁relations ▁must ▁be ▁un bounded , ▁the ▁Baker – C amp bell – H aus dor ff ▁formula ▁does ▁not ▁apply ▁without ▁additional ▁domain ▁assumptions . ▁Indeed , ▁counter examples ▁exist ▁satisfying ▁the ▁canonical