What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? John is running. Charles is not writing a letter. Charles is a mechanic if and only if Joseph is curious. For all x_16, x_16 is a mechanic if and only if x_16 will write a letter.
John is running and Charles is not writing a letter. Charles is not writing a letter and John is running. If Charles were a mechanic, then Joseph is curious. If Joseph were curious, then Charles is a mechanic. For all x_16, if x_16 were a mechanic, then x_16 is writing a letter. For all x_16, if x_16 writes a letter, then x_16 is a mechanic.