CONTENTSIntroduction...................................................................................5§1. Preliminaries...........................................................................7§2. Definitions and a theorem of Diestel, Faires and Huff.............9§3. Examples...............................................................................13§4. Some special classes of Boolean algebras ..........................19§5. The Grothendieck property...................................................22§6....
                    
                 
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                    
                       
The dual attainment of the Monge–Kantorovich transport problem is analyzed in a general setting. The spaces  are assumed to be polish and equipped with Borel probability measures  and . The transport cost function  :  ×  →  [0,∞]  is assumed to be Borel measurable. We show that a dual optimizer always exists, provided we interpret it as a projective limit of certain finitely additive measures. Our methods are functional analytic and rely on Fenchel’s perturbation technique.
                    
                 
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                    
                       
      The duality theory for the Monge-Kantorovich transport problem is analyzed in a general setting. The spaces X,Y are assumed to be Polish and equipped with Borel probability measures μ and ν. The transport cost function c: X × Y → [0,∞] is assumed to be Borel. Our main result states that in this setting there is no duality gap provided the optimal transport problem is formulated in a suitably relaxed way. The relaxed transport problem is defined as the limiting cost of the partial transport...
                    
                 
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                    
                       
The following question is due to Marc Yor: Let  be a brownian motion and 
               =+
               . Can we define an -predictable process  such that the resulting stochastic integral (⋅) is a brownian motion (without drift) in its own filtration, i.e. an -brownian motion? In this paper we show that by dropping the requirement of -predictability of  we can give a positive answer to this question. In other words, we are able to show that there is a weak solution to Yor’s question. The original...
                    
                 
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
            
                
             
            
            
                
            
            
            
                
                    
                
            
            
            
            
                
            
            
             
            
                
            
            
            
                
                
                
                    
                       
The dual attainment of the Monge–Kantorovich transport problem is analyzed in a general
          setting. The spaces  are assumed to be polish and equipped with Borel
          probability measures  and . The transport cost
          function  :  ×  →  [0,∞]  is assumed
          to be Borel measurable. We show that a dual optimizer always exists, provided we interpret
          it as a projective limit of certain finitely additive measures. Our methods are functional
          analytic and rely...
                    
                 
                
                    
                
            
        
            
            
            
            
            
                
            
                
            
                
            
                
            
                
                    
                
            
                
             
            
            
                
            
            
            
                
            
            
            
            
                
                    
                
            
            
             
            
                
            
            
            
                
                
                
                
                    
                
            
        
        
        
            
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