Gremlin query how to compare properties of edges in same branch of my traversal?

Question

I'm struggling to write a gremlin query that compares the values of each edge of a given branch of my traversal to both each other and a provided value.

Here's an example - let's say I have the following hierarchy composed of Schools, Teams, and Athletes, any of which can be connected to a Uniform via a wears edge. And let's also say I record the creation date of every edge as a property in that edge called created. In any possible branch, like the one highlighted in blue, I need to query for maximum(wears.created, establishes.created, recruits.created) >= 2009.

How can I display every uniform an athlete ever wore since 2009 along with the date they began wearing it?

Sometimes that date is the year an Athlete was recruited onto a Team, sometimes it's the year a School established a Team, and other times it's whenever an individual Athlete, Team, or School began wearing a new Uniform.

I need a way to select the maximum creation date of all edges in a branch (like the one in blue above) and then also to compare that maximum to the provided date of 2009.

Something like this maybe? Is anything like this possible in gremlin??

g.V().hasLabel("Athlete").as("athlete").union(
    __.outE("wears").has("created", P.gte(2009)).as("when").by("created"),
    __.inE("recruits").as("r").by("created").outV().hasLabel("Team")
        .outE("wears").as("w").by("created")
        .select(max("r", "w")).as("when")
        .where("when", P.gte(2009))
    __.inE("recruits").as("r").by("created").outV().hasLabel("Team")
        .inE("establishes").as("e").by("created").outV().hasLabel("School")
        .outE("wears").as("w").by("created")
        .select(max("r", "e", "w")).as("when")
        .where("when", P.gte(2009))
).inV().hasLabel("Uniform").as("uniform")
.select("athlete", "uniform", "when")

<== Edit =================================================>

Adding a startup script to assist in testing as per the comment by Steven Mallette.

g.addV('School').property('id',1).property("name", "Duke").as('duke').
  addV('School').property('id',2).property("name", "UNC").as('unc').
  addV('Team').property('id',3).property("name", "Soccer").as('soccer').
  addV('Team').property('id',4).property("name", "Football").as('football').
  addV('Team').property('id',5).property("name", "Basketball").as('basketball').
  addV('Athlete').property('id',6).property("name", "Joe").as('joe').
  addV('Athlete').property('id',7).property("name", "Jane").as('jane').
  addV('Athlete').property('id',8).property("name", "Alice").as('alice').
  addV('Athlete').property('id',9).property("name", "Bob").as('bob').
  addV('Uniform').property('id',10).property("color", "red").as('red').
  addV('Uniform').property('id',11).property("color", "pink").as('pink').
  addV('Uniform').property('id',12).property("color", "blue").as('blue').
  addV('Uniform').property('id',13).property("color", "teal").as('teal').
  addV('Uniform').property('id',14).property("color", "green").as('green').
  addE('contains').property("created", 2009).from('duke').to('soccer').
  addE('contains').property("created", 1960).from('unc').to('football').
  addE('contains').property("created", 2007).from('duke').to('basketball').
  addE('contains').property("created", 2016).from('soccer').to('bob').
  addE('contains').property("created", 2008).from('basketball').to('jane').
  addE('contains').property("created", 2010).from('basketball').to('alice').
  addE('contains').property("created", 2015).from('football').to('joe').
  addE('wears').property("created", 2009).from('duke').to('blue').
  addE('wears').property("created", 1999).from('unc').to('red').
  addE('wears').property("created", 2010).from('soccer').to('teal').
  addE('wears').property("created", 2009).from('football').to('pink').
  addE('wears').property("created", 2009).from('basketball').to('teal').
  addE('wears').property("created", 2012).from('alice').to('green')

With the expected output being the following (Adding the output per Daniel Kuppitz's suggestion). To explain the first line of the output: Jane wears teal since 2009 because the basketball team formed in 2007 at duke, Jane joined the team in 2008, but the basketball team started wearing teal in 2009, so 2009 is the maximum date for Jane and this Uniform.

Jane wears teal since 2009
Jane wears blue since 2009
Alice wears teal since 2010
Alice wears blue since 2010
Alice wears green since 2012
Joe wears pink since 2015
Joe wears red since 2015
Bob wears blue since 2016
Bob wears teal since 2016

Answer 1

Hopefully the final edit after the most recent comments (but the result now matches your expected result, so I think we're good):

gremlin> g.V().hasLabel("Athlete").as("a").
           union(outE("wears").sack(assign).by("created"),
                 inE("contains").sack(assign).by("created").outV().
                 union(outE("wears").sack(max).by("created"),
                       inE("contains").sack(max).by("created").outV().
                       outE("wears").sack(max).by("created"))).
           filter(sack().is(gte(2009))).
           project("athlete","when","uniform").
             by(select("a").by("name")).
             by(sack()).
             by(inV().values("color"))
==>[athlete:Joe,when:2015,uniform:pink]
==>[athlete:Joe,when:2015,uniform:red]
==>[athlete:Jane,when:2009,uniform:teal]
==>[athlete:Jane,when:2009,uniform:blue]
==>[athlete:Alice,when:2012,uniform:green]
==>[athlete:Alice,when:2010,uniform:teal]
==>[athlete:Alice,when:2010,uniform:blue]
==>[athlete:Bob,when:2016,uniform:teal]
==>[athlete:Bob,when:2016,uniform:blue]

Or, since your schema is pretty uniform, you can actually use repeat() and thus get rid of the unreadable nested union()'s:

gremlin> g.withSack(0).V().hasLabel("Athlete").as("a").
           emit().
             repeat(inE("contains").sack(max).by("created").outV()).
             times(2).
           outE("wears").sack(max).by("created").
           filter(sack().is(gte(2009))).
           project("athlete","when","uniform").
             by(select("a").by("name")).
             by(sack()).
             by(inV().values("color"))
==>[athlete:Joe,when:2015,uniform:pink]
==>[athlete:Joe,when:2015,uniform:red]
==>[athlete:Jane,when:2009,uniform:teal]
==>[athlete:Jane,when:2009,uniform:blue]
==>[athlete:Alice,when:2012,uniform:green]
==>[athlete:Alice,when:2010,uniform:teal]
==>[athlete:Alice,when:2010,uniform:blue]
==>[athlete:Bob,when:2016,uniform:teal]
==>[athlete:Bob,when:2016,uniform:blue]