From: PopMod: a longitudinal population model with two interacting disease states

Logical expression | Meaning | Differential equations expression |
---|---|---|

~ X~ C | Population group with neither X nor C | S |

X~ C | Population group with X but not C, i.e. with X only | X |

~ XC | Population group with C but not X, i.e. with C only | C |

~ X | Population group without X | S + C |

~ C | Population group without C | S + X |

X | Total population group with X | X + XC |

C | Total population group with C | C + XC |

S | Susceptible population | S |

XC | Population with both X and C | XC |

T | Total population | T |