reserve x for set,
  D for non empty set,
  k,n,m,i,j,l for Nat,
  K for Field;
reserve n,i,j for Nat;

theorem Th76:
  1<=j & j<=n & i<>j implies (Base_FinSeq(n,i)).j=0
proof
  assume that
A1: 1<=j & j<=n and
A2: i<>j;
A3: j in Seg n by A1;
  thus (Base_FinSeq(n,i)).j = (n |-> 0).j by A2,FUNCT_7:32
    .= 0 by A3,FINSEQ_2:57;
end;
