requirements.json

[
    {
        "example": "Photo sharing social network",
        "model": "sig User { follows : set User, sees : set Photo, posts : set Photo, suggested : set User } sig Influencer extends User {} sig Photo { date : one Day } sig Ad extends Photo {} sig Day {}",
        "id": "x3JXgWhJ3uti5Dzxz",
        "requirements": [
            {
                "description": "Every photo is posted by one user",
                "pred":"this/inv1"
            },
            {
                "description": "Users cannot follow themselves",
                "pred":"this/inv2"
            },
            {
                "description": "Users can see ads posted by everyone, but only see non ads posted by followed users",
                "pred":"this/inv3"
            },
            {
                "description": "If a user posts an ad then all its posts should be labeled as ads",
                "pred":"this/inv4"
            },
            {
                "description": "Influencers are followed by everyone else",
                "pred":"this/inv5"
            },
            {
                "description": "Influencers post every day",
                "pred":"this/inv6"
            },
            {
                "description": "Suggested are other users followed by followed users, but not yet followed",
                "pred":"this/inv7"
            },
            {
                "description": "A user only sees ads from followed or suggested users",
                "pred":"this/inv8"
            }
        ]
    },
    {
        "example": "Production line",
        "model": "sig Workstation { workers : set Worker, succ : set Workstation } one sig begin, end in Workstation {} sig Worker {} sig Human, Robot extends Worker {} abstract sig Product { parts : set Product } sig Material extends Product {} sig Component extends Product { workstation : set Workstation } sig Dangerous in Product {}",
        "id": "dyj49tEp7j6aWAQQX",
        "requirements": [
            {
                "description": "Workers are either human or robots",
                "pred":"this/inv1"
            },
            {
                "description": "Every workstation has workers and every worker works in one workstation",
                "pred":"this/inv2"
            },
            {
                "description": "Every component is assembled in one workstation",
                "pred":"this/inv3"
            },
            {
                "description": "Components must have parts and materials have no parts",
                "pred":"this/inv4"
            },
            {
                "description": "Humans and robots cannot work together",
                "pred":"this/inv5"
            },
            {
                "description": "Components cannot be their own parts",
                "pred":"this/inv6"
            },
            {
                "description": "Components built of dangerous parts are also dangerous",
                "pred":"this/inv7"
            },
            {
                "description": "Dangerous components cannot be assembled by humans",
                "pred":"this/inv8"
            },
            {
                "description": "The workstations form a single line between begin and end",
                "pred":"this/inv9"
            },
            {
                "description": "The parts of a component must be assembled before it in the production line",
                "pred":"this/inv10"
            }
        ]
    },
    {
        "example": "Train station",
        "model": "sig Track { succs : set Track, signals : set Signal } sig Junction, Entry, Exit in Track {} sig Signal {} sig Semaphore, Speed extends Signal {}",
        "id": "cXPP9QBPTYgTX6WJ6",
        "requirements": [
            {
                "description": "The station has at least one entry and one exit",
                "pred": "this/inv1"
            },
            {
                "description": "Signals belong to one track",
                "pred": "this/inv2"
            },
            {
                "description": "Exit tracks are those without successor",
                "pred": "this/inv3"
            },
            {
                "description": "Entry tracks are those without predecessors",
                "pred": "this/inv4"
            },
            {
                "description": "Junctions are the tracks with more than one predecessor",
                "pred": "this/inv5"
            },
            {
                "description": "Entry tracks must have a speed signal",
                "pred": "this/inv6"
            },
            {
                "description": "The station has no cycles",
                "pred": "this/inv7"
            },
            {
                "description": "It should be possible to reach every exit from every entry",
                "pred": "this/inv8"
            },
            {
                "description": "Tracks not followed by junctions do not have semaphores",
                "pred": "this/inv9"
            },
            {
                "description": "Every track before a junction has a semaphore",
                "pred": "this/inv10"
            }
        ]
    },
    {
        "example": "Courses",
        "model": "open util/ordering[Grade] sig Person { teaches : set Course, enrolled : set Course, projects : set Project } sig Professor,Student in Person {} sig Course { projects : set Project, grades : Person -> Grade } sig Project {} sig Grade {}",
        "id": "iP5JL36afv5KbDKP6",
        "requirements": [
            {
                "description": "Only students can be enrolled in courses",
                "pred": "this/inv1"
            },
            {
                "description": "Only professors can teach courses",
                "pred": "this/inv2"
            },
            {
                "description": "Courses must have teachers",
                "pred": "this/inv3"
            },
            {
                "description": "Projects are proposed by one course",
                "pred": "this/inv4"
            },
            {
                "description": "Only students work on projects and projects must have someone working on them",
                "pred": "this/inv5"
            },
            {
                "description": "Students only work on projects of courses they are enrolled in",
                "pred": "this/inv6"
            },
            {
                "description": "Students work on at most one project per course",
                "pred": "this/inv7"
            },
            {
                "description": "A professor cannot teach herself",
                "pred": "this/inv8"
            },
            {
                "description": "A professor cannot teach colleagues",
                "pred": "this/inv9"
            },
            {
                "description": "Only students have grades",
                "pred": "this/inv10"
            },
            {
                "description": "Students only have grades in courses they are enrolled",
                "pred": "this/inv11"
            },
            {
                "description": "Students have at most one grade per course",
                "pred": "this/inv12"
            },
            {
                "description": "A student with the highest mark in a course must have worked on a project on that course",
                "pred": "this/inv13"
            },
            {
                "description": "A student cannot work with the same student in different projects",
                "pred": "this/inv14"
            },
            {
                "description": "Students working on the same project in a course cannot have marks differing by more than one unit",
                "pred": "this/inv15"
            }
        ]
    }
]