| No TPTP formula. May not be expressible in strict first order. | Mid-level-ontology.kif 1687-1687 | Fossil fuel is a subclass of fuel |
| No TPTP formula. May not be expressible in strict first order. | Mid-level-ontology.kif 1688-1688 | Fossil fuel is a subclass of petroleum product |
| No TPTP formula. May not be expressible in strict first order. | Mid-level-ontology.kif 1705-1705 | Liquefied petroleum gas is a subclass of fossil fuel |
| No TPTP formula. May not be expressible in strict first order. | Mid-level-ontology.kif 1709-1709 | Gasoline is a subclass of fossil fuel |
| No TPTP formula. May not be expressible in strict first order. | Mid-level-ontology.kif 1714-1714 | Diesel fuel is a subclass of fossil fuel |
| No TPTP formula. May not be expressible in strict first order. | Geography.kif 2018-2018 | Coal is a subclass of fossil fuel |
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