| FailureReason | Otter.SearchRes, Otter, Zsyntax | 
| filterImpl | Zsyntax.Labelled.Rule.Frontier, Zsyntax.Labelled.Rule | 
| filterUnsubsumed | Otter.Internal.Search | 
| FKind | Zsyntax.Labelled.Formula | 
| foc | Zsyntax.Labelled.Rule.Frontier, Zsyntax.Labelled.Rule | 
| FocMatchRes | Zsyntax.Labelled.Rule.BipoleRelation, Zsyntax.Labelled.Rule | 
| focus | Zsyntax.Labelled.Rule.BipoleRelation, Zsyntax.Labelled.Rule | 
| foldActives | Otter.Internal.Structures | 
| Formula |   | 
| 1 (Type/Class) | Zsyntax.Formula, Zsyntax | 
| 2 (Data Constructor) | Zsyntax.Formula, Zsyntax | 
| frmlHetEq | Zsyntax.Labelled.Formula | 
| frmlHetOrd | Zsyntax.Labelled.Formula | 
| frNeg | Zsyntax.Labelled.Rule.Frontier, Zsyntax.Labelled.Rule | 
| fromCSCtxts | Zsyntax.ReactionList | 
| frontier | Zsyntax.Labelled.Rule.Frontier, Zsyntax.Labelled.Rule | 
| frPos | Zsyntax.Labelled.Rule.Frontier, Zsyntax.Labelled.Rule | 
| FSChecked | Otter.Internal.Structures | 
| FSCheckedNode | Otter.Internal.Structures | 
| FullXiEmptyResult | Zsyntax.Labelled.Rule.Interface, Zsyntax.Labelled.Rule | 
| FullZetaXi | Zsyntax.Labelled.Rule.Interface, Zsyntax.Labelled.Rule | 
| fwdSubsumes | Otter.Internal.Structures |