lˈɛt biː ɐ sˌɛmɪsˈɪmpəl lˈaɪ ˈældʒᵻbɹə,  ɪts kˈɑːɹtən sˈʌbɐldʒˌɛbɹə ænd biː tˈuː ˈɛlɪmənts ʌvðə wˈeɪt spˈeɪs wˌɛɹ ɪz ðə dˈuːəl ʌv ænd ɐsˈuːm ðˌæɾə sˈɛt ʌv pˈɑːzᵻtˌɪv ɹˈuːts hɐvbɪn fˈɪkst.
Let  be a semisimple Lie algebra,  its Cartan subalgebra and  be two elements of the weight space (where  is the dual of ) and assume that a set of positive roots  have been fixed.