diff --git a/thys/Topological_Semantics/ROOT b/thys/Topological_Semantics/ROOT
--- a/thys/Topological_Semantics/ROOT
+++ b/thys/Topological_Semantics/ROOT
@@ -1,28 +1,28 @@
 chapter AFP
 
 session "Topological_Semantics" (AFP) = "HOL" +
   options [timeout = 600]
   theories
-	sse_boolean_algebra
-	sse_boolean_algebra_quantification
-	sse_operation_positive
-	sse_operation_positive_quantification
-	sse_operation_negative
-	sse_operation_negative_quantification
-	topo_operators_basic
-	topo_operators_derivative
-	topo_alexandrov
-	topo_frontier_algebra
-	topo_negation_conditions
-	topo_negation_fixedpoints
-	ex_LFIs
-	topo_strict_implication
-	ex_subminimal_logics
-	topo_derivative_algebra
-	ex_LFUs
-	topo_border_algebra
-	topo_closure_algebra
-	topo_interior_algebra
+    sse_boolean_algebra
+    sse_boolean_algebra_quantification
+    sse_operation_positive
+    sse_operation_positive_quantification
+    sse_operation_negative
+    sse_operation_negative_quantification
+    topo_operators_basic
+    topo_operators_derivative
+    topo_alexandrov
+    topo_frontier_algebra
+    topo_negation_conditions
+    topo_negation_fixedpoints
+    ex_LFIs
+    topo_strict_implication
+    ex_subminimal_logics
+    topo_derivative_algebra
+    ex_LFUs
+    topo_border_algebra
+    topo_closure_algebra
+    topo_interior_algebra
   document_files
     "root.tex"
-    "root.bib"   
+    "root.bib"