Body: <p>A fun mating problem for a change, for my chess kiddies: White has two kings, one is an &quot;erlking&quot; (as the problemists call it), moving like a king but doesn't have to care about checks and can be captured (as in losing chess).</p>
  <p>Problem with mating K+E vs. K: The black king can try to run for the hills, and, so to say, is doubly as fast since both kings must come running after. What is the maximum board size for this mate (if at all)?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-11-07T18:03:24.957Z
Comments.Text: Are we assuming the board size is square?
  On narrow rectangular boards the K+E easily win, 
  but we can still ask for the inclusion-maximal rectangles 
  on which the K+E have a forced mate.
Comments.UserDisplayName: Noam D. Elkies
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-11-08T09:07:44.700Z
Comments.Text: Yes, the board is square, but feel free to generalize. (A related setup which might be easier to handle: Infinite one-edged board, bKa1, where must K+E stand to be able to box the bK in?)
Comments.UserDisplayName: Hauke Reddmann
Tags: <endgame><chess-variants>
Title: Maximum board size for mating with a non-royal king
ThreadText: # Maximum board size for mating with a non-royal king
  
  (Asked by: username_0 on 2024-11-07)
  
  A fun mating problem for a change, for my chess kiddies: White has two kings, one is an "erlking" (as the problemists call it), moving like a king but doesn't have to care about checks and can be captured (as in losing chess).
  
  Problem with mating K+E vs. K: The black king can try to run for the hills, and, so to say, is doubly as fast since both kings must come running after. What is the maximum board size for this mate (if at all)?
  
  **Tags:** endgame, chess-variants
  
  > **Comments:**
  > **username_1**: Are we assuming the board size is square? On narrow rectangular boards the K+E easily win,  but we can still ask for the inclusion-maximal rectangles  on which the K+E have a forced mate.  
  > **username_0**: Yes, the board is square, but feel free to generalize. (A related setup which might be easier to handle: Infinite one-edged board, bKa1, where must K+E stand to be able to box the bK in?)  
  
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  ## 0 answers
  
  