reserve p for Point of TOP-REAL 2,
  f,f1,f2,g for FinSequence of TOP-REAL 2,
  v, v1,v2 for FinSequence of REAL,
  r,s for Real,
  n,m,i,j,k for Nat,
  x for set;
reserve G for Go-board;

theorem
  width G = m+1 & m>0 & k in Seg m implies Col(DelCol(G,width G),k) =
  Col(G,k) & k in Seg width DelCol(G,width G) by MATRIX_0:73;
