~ an householder which ~ , 40_MAT_13_52 , 40_MAT_20_01 , 
~ is an householder which ~ , 40_MAT_13_52 , 40_MAT_20_01 , 
~ is an householder ~ , 40_MAT_13_52 , 40_MAT_20_01 , 
~ that is an householder ~ , 40_MAT_13_52 , 40_MAT_20_01 ,