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 Th8:
  i in Seg width G & width G = m+1 & m>0 & n in dom G & 1<=k & k<i
  implies DelCol(G,i)*(n,k) = G*(n,k) & k in Seg width G by MATRIX_0:69;
