By Monitor The Israeli/Palestinian situation is difficult enough to understand and follow without the further confusion that arises because apparently the Palestinans have two presidents: Abu Mazen and Mahmoud Abbas. In fact they are one and the same person but some people, among them journalists, prefer the former name and others the latter. In a statement last Sunday the Israeli prime minister Ariel Sharon referred to Abu Mazen but he has spoken of Mahmoud Abbas on other occasions in the past. Perhaps, if the two sides can agree on nothing else, they could agree to standardise the Palestinian president's name, if necessary by calling him Mazen-Abbas. Mr Sharon's statement was the latest of the series in which he has done everything to queer Mahmoud Abbas's pitch, which is difficult enough without this help. Having agreed to free 400 Palestinian prisoners in negotiations with Mr Abbas soon after he was elected, Sharon has now frozen their release. Explaining his decision, he said: Let me be clear, there will be no prisoner release before steps are taken against terror. Everyone asks me to strengthen Abu Massen, but I tell them not at the expense of Israeli lives. The Israelis have also stopped the transfer of authority in three West Bank towns, alleging that the Palestinians have not disarmed militants. On the face of it, Mr Sharon is asking for the impossible, nothing less than a castiron guarantee from the Palestinian Authority that there will be a total cessation of violence from Palestinian militants for the indefinite future. Mahmoud Abbas cannot provide any such guarantee any more than Ariel Sharon can promise that the Israeli military will not kill any Palestinian. The real reason for Mr Sharon's tough line is to impress the critics of his plans for withdrawing from the Gaza settlements. But in the process he is making the prospect for peace ever more distant.