CLang: The RoboCup Coach Language

The RoboCup Coach Language (CLang) was developed to enable online coaches to change the behavior of simulated soccer players during games in the Simulated League. Since a coach may work together with teams from different research groups, it is important for the coach language to have clear semantics that prevent misinterpretation from both the players and the coach.

The CLang grammar that is used in our corpus is based on the one given in the following document (Section 7.7):

Mao Chen, Klaus Dorer, Ehsan Foroughi, Fredrik Heintz, ZhanXiang Huang, Spiros Kapetanakis, Kostas Kostiadis, Johan Kummeneje, Jan Murray, Itsuki Noda, Oliver Obst, Pat Riley, Timo Steffens, Yi Wang and Xiang Yin. RoboCup Soccer Server Users Manual, for Soccer Server Version 7.07 and later. February 11, 2003.

CLang was not designed for use with an NL interface. To make it easier to use, we have modified CLang, guided by the following principles:

1. If a construct is too clumsy to describe using natural languages, then a more common specialization of the construct is introduced. For example, (arc POINT 0 RADIUS 0 360) becomes (circle POINT RADIUS).
2. If there are simple concepts that can be easily described in natural languages, but are impossible to express in CLang, then new constructs that correspond to these concepts are introduced. For example, (left REGION) is a new construct that refers to the left half of REGION from our team's perspective.
3. New constructs may be introduced by symmetry. For example, the player predicate is introduced alongside player-except and player-range, so that players can be referenced in a unified manner.
4. It must be easy to convert the new constructs back into CLang for use in the RoboCup Soccer Server.

Here are the modifications that have been made:

1. All references to players are made using the following constructs:
   • (player TEAM UNUM_SET) - the players in the team TEAM whose uniform number is in the set UNUM_SET.
   • (player-except TEAM UNUM_SET) - the players in the team TEAM whose uniform number is not in the set UNUM_SET.
   • (player-range TEAM UNUM₁ UNUM₂) - the players in the team TEAM whose uniform number is between UNUM₁ and UNUM₂ (inclusive).
   All constructs that contain references to individual players are made to accept player, player-except and player-range as arguments. For example, (bowner our {6}) becomes (bowner (player our {6})). (pass {2}) becomes (pass (player our {2})).
2. (ppos TEAM UNUM_SET INT₁ INT₂ REGION) becomes:
   • (ppos-any (player TEAM UNUM_SET) REGION) if INT₁ is 1 and INT₂ is greater than or equal to the size of UNUM_SET. (This corresponds to the ppos-all predicate that appeared in earlier versions of the CLang corpus. ppos-any is a more appropriate name than ppos-all.)
   • (ppos-none TEAM REGION) if UNUM_SET is {0} and both INT₁ and INT₂ are zero.
3. (POINT₁ + ((pt ball) * POINT₂)) becomes (pt-with-ball-attraction POINT₁ POINT₂).
4. (arc POINT 0 RADIUS ANGLE_BEGIN 360) becomes (circle POINT RADIUS), regardless of the value of ANGLE_BEGIN.
5. New constructs are introduced for the following pre-defined regions:
   • Rectangles:
     • (field) - the entire field.
     • (half TEAM) - the TEAM's half of the field.
     • (penalty-area TEAM) - the TEAM's penalty area.
     • (goal-area TEAM) - the TEAM's goal area.
     • (midfield) - the entire midfield.
     • (midfield TEAM) - the TEAM's half of the midfield.
     • (near-goal-line TEAM) - the area near the TEAM's goal line. (The very-near-goal-line predicate, which appeared in previous versions of the CLang corpus, becomes near-goal-line. There was previously only one instance of very-near-goal-line in the corpus, and the two predicates are semantically very similar.)
     • (from-goal-line TEAM X₁ X₂) - X₁ to X₂ meters from the TEAM's goal line.
     • (left REGION) - the left half of REGION from our team's perspective.
     • (right REGION) - the right half of REGION from our team's perspective.
     • (left-quarter REGION) - the left quarter of REGION from our team's perspective.
     • (right-quarter REGION) - the right quarter of REGION from our team's perspective.
     • (reg-exclude REGION₁ REGION₂) - the region REGION₁ minus REGION₂. (This construct is used only when it results in a rectangular region.)
   • Points:
     • (front-of-goal TEAM) - the point directly in front of the TEAM's goal.
     • (from-goal TEAM X) - the point X meters in front of the TEAM's goal.

Code that translates the new CLang constructs into the original CLang (and the pre-defined regions into exact xy-coordinates) is available upon request.

Yuk Wah Wong (ywwong@cs.utexas.edu)