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
  i in Seg width G & width G = m+1 & m>0 & i<=k & k<=m implies Col
(DelCol(G,i),k) = Col(G,k+1) & k in Seg width DelCol(G,i) & k+1 in Seg width G
     by MATRIX_0:68;
