THE PROBLEM OF PHASE TRANSITIONS

The following sections are included:

• THE THEOREM OF LEE AND YANG

• ABSENCE OF PHASE TRANSITIONS AT HIGH TEMPERATURE

• EXISTENCE OF A FIRST–RDER PHASE TRANSITION AT LOW TEMPERATURE

• THE GRIFFITHS INEQUALITIES

• THE THEOREM OF MERMIN AND WAGNER

• ONE–DIMENSIONAL SYSTEMS

• THE NOTION OF PHASE TRANSITION

• BIBLIOGRAPHICAL NOTE

• EXERCISES