PPT-preserving operations

What computable expression, if any, equals the regularized exact PPT distillable entanglement of a bipartite state?

• Quantum Resource Theory
• Entanglement distillation
• PPT-preserving operations
• Additivity and regularization
• One-shot and finite-blocklength bounds

Consider distilling the bipartite Bell-diagonal state

• Quantum Resource Theory
• Entanglement distillation
• PPT-preserving operations
• Bell-diagonal states