path: root/src/algebra/tree.spad.pamphlet

\documentclass{article}
\usepackage{open-axiom}
\begin{document}
\title{\$SPAD/src/algebra tree.spad}
\author{William Burge}
\maketitle
\begin{abstract}
\end{abstract}
\eject
\tableofcontents
\eject

\section{domain TREE Tree}

<<domain TREE Tree>>=
import Boolean
import List
)abbrev domain TREE Tree
++ Author:W. H. Burge
++ Date Created:17 Feb 1992
++ Date Last Updated:
++ Basic Operations:
++ Related Domains:
++ Also See:
++ AMS Classifications:
++ Keywords:
++ Examples:
++ References:
++ Description: \spadtype{Tree(S)} is a basic domains of tree structures.
++ Each tree is either empty or else is a {\it node} consisting of a value and
++ a list of (sub)trees.
Tree(S: SetCategory): T==C where
 T== Join(RecursiveAggregate S,FiniteAggregate S,ShallowlyMutableAggregate S) with
     tree: (S,List %) -> %
       ++ tree(nd,ls) creates a tree with value nd, and children
       ++ ls.
     tree: List S -> %
       ++ tree(ls) creates a tree from a list of elements of s. 
     tree: S -> %
       ++ tree(nd) creates a tree with value nd, and no children
     cyclic?: % -> Boolean
       ++ cyclic?(t) tests if t is a cyclic tree.
     cyclicCopy: % -> %
      ++ cyclicCopy(l) makes a copy of a (possibly) cyclic tree l.
     cyclicEntries:    % -> List %
       ++ cyclicEntries(t) returns a list of top-level cycles in tree t.
     cyclicEqual?: (%, %) -> Boolean
       ++ cyclicEqual?(t1, t2) tests of two cyclic trees have 
       ++ the same structure.
     cyclicParents: % -> List %
       ++ cyclicParents(t) returns a list of cycles that are parents of t.
 C== add
    cycleTreeMax ==> 5

    Rep := Union(node:Record(value: S, args: List %),empty:"empty")
    empty? t == t case empty
    empty()  == ["empty"]
    children t == 
      t case empty => error "cannot take the children of an empty tree" 
      (t.node.args)@List(%)
    setchildren!(t,lt) == 
      t case empty => error "cannot set children of an empty tree"
      (t.node.args:=lt;t pretend %)
    setvalue!(t,s) == 
      t case empty => error "cannot set value of an empty tree"
      (t.node.value:=s;s)
    count(n: S, t: %) == 
      t case empty => 0
      i := +/[count(n, c) for c in children t]
      value t = n => i + 1
      i
    count(fn: S -> Boolean, t: %): NonNegativeInteger ==
      t case empty => 0
      i := +/[count(fn, c) for c in children t]
      fn value t => i + 1
      i
    map(fn, t) == 
      t case empty => t
      tree(fn value t,[map(fn, c) for c in children t])
    map!(fn, t) == 
      t case empty => t
      setvalue!(t, fn value t)
      for c in children t repeat map!(fn, c)
      t
    tree(s,lt) == [[s,lt]]
    tree(s: S) == [[s,[]]]
    tree(ls: List S) ==
      empty? ls => empty()
      tree(first ls, [tree s for s in rest ls])
    value t ==
      t case empty => error "cannot take the value of an empty tree" 
      t.node.value
    child?(t1,t2) == 
      empty? t2 => false
      "or"/[t1 = t for t in children t2]
    distance1(t1: %, t2: %): Integer ==
      t1 = t2 => 0
      t2 case empty => -1
      u := [n for t in children t2 | (n := distance1(t1,t)) >= 0]
      positive?(#u) => 1 + "min"/u 
      -1 
    distance(t1,t2) == 
      n := distance1(t1, t2)
      n >= 0 => n
      distance1(t2, t1)
    node?(t1, t2) ==
      t1 = t2 => true
      t2 case empty => false
      "or"/[node?(t1, t) for t in children t2]
    leaf? t == 
      t case empty => false
      empty? children t
    leaves t == 
      t case empty => empty()
      leaf? t => [value t]
      "append"/[leaves c for c in children t]
    nodes t ==       ---buggy
      t case empty => empty()
      nl := [nodes c for c in children t]
      nl = empty() => [t]
      cons(t,"append"/nl)
    any?(fn, t) ==  ---bug fixed
      t case empty => false
      fn value t or "or"/[any?(fn, c) for c in children t]
    every?(fn, t) == 
      t case empty => true
      fn value t and "and"/[every?(fn, c) for c in children t]
    member?(n, t) == 
      t case empty => false
      n = value t or "or"/[member?(n, c) for c in children t]
    members t == --buggy?
      t case empty => empty()
      u := [members c for c in children t]
      u = empty() => [value t]
      cons(value t,"append"/u)
 
    ---Functions that guard against cycles: =, #, copy-------------

    -----> =   
    equal?: (%, %, %, %, Integer) -> Boolean

    t1 = t2 == equal?(t1, t2, t1, t2, 0) 

    equal?(t1, t2, ot1, ot2, k) ==
      k = cycleTreeMax and (cyclic? ot1 or cyclic? ot2) => 
        error "use cyclicEqual? to test equality on cyclic trees"
      t1 case empty => t2 case empty
      t2 case empty => false
      value t1 = value t2 and (c1 := children t1) = (c2 := children t2) and
        "and"/[equal?(x,y,ot1, ot2,k + 1) for x in c1 for y in c2]

    -----> #
    treeCount: (%, %, NonNegativeInteger) -> NonNegativeInteger    
    # t == treeCount(t, t, 0)
    treeCount(t, origTree, k) ==
      k = cycleTreeMax and cyclic? origTree => 
        error "# is not defined on cyclic trees"
      t case empty => 0
      1 + +/[treeCount(c, origTree, k + 1) for c in children t]
 
    -----> copy
    copy1: (%, %, Integer) -> %
    copy t == copy1(t, t, 0)
    copy1(t, origTree, k) == 
      k = cycleTreeMax and cyclic? origTree => 
        error "use cyclicCopy to copy a cyclic tree"
      t case empty  => t
      empty? children t => tree value t
      tree(value t, [copy1(x, origTree, k + 1) for x in children t])
      
    -----------Functions that allow cycles---------------
    --local utility functions:
    eqUnion: (List %, List %) -> List %
    eqMember?: (%, List %) -> Boolean
    eqMemberIndex: (%, List %, Integer) -> Integer
    lastNode: List % -> List %
    insert: (%, List %) -> List %

    -----> coerce to OutputForm
    if S has CoercibleTo(OutputForm) then
      multipleOverbar: (OutputForm, Integer, List %) -> OutputForm
      coerce1: (%, List %, List %) -> OutputForm

      coerce(t:%): OutputForm == coerce1(t, empty()$(List %), cyclicParents t)

      coerce1(t,parents, pl) ==
        t case empty => empty()@List(S)::OutputForm
        eqMember?(t, parents) => 
          multipleOverbar((".")::OutputForm,eqMemberIndex(t, pl,0),pl)
        empty? children t => value t::OutputForm
        nodeForm := (value t)::OutputForm
        if positive?(k := eqMemberIndex(t, pl, 0)) then
           nodeForm := multipleOverbar(nodeForm, k, pl)
        prefix(nodeForm, 
          [coerce1(br,cons(t,parents),pl) for br in children t])

      multipleOverbar(x, k, pl) ==
        k < 1 => x
        #pl = 1 => overbar x
        s : String := "abcdefghijklmnopqrstuvwxyz"
        c := s.(1 + ((k - 1) rem 26))
        overlabel(c::OutputForm, x)
 
    -----> cyclic?
    cyclic2?: (%, List %) -> Boolean

    cyclic? t == cyclic2?(t, empty()$(List %))

    cyclic2?(x,parents) ==  
      empty? x => false
      eqMember?(x, parents) => true
      for y in children x repeat
        cyclic2?(y,cons(x, parents)) => return true
      false
 
    -----> cyclicCopy
    cyclicCopy2: (%, List %) -> %
    copyCycle2: (%, List %) -> %
    copyCycle4: (%, %, %, List %) -> %

    cyclicCopy(t) == cyclicCopy2(t, cyclicEntries t)

    cyclicCopy2(t, cycles) ==
      eqMember?(t, cycles) => copyCycle2(t, cycles)
      tree(value t, [cyclicCopy2(c, cycles) for c in children t])
   
    copyCycle2(cycle, cycleList) == 
      newCycle := tree(value cycle, nil)
      setchildren!(newCycle,
        [copyCycle4(c,cycle,newCycle, cycleList) for c in children cycle])
      newCycle

    copyCycle4(t, cycle, newCycle, cycleList) == 
      empty? cycle => empty()
      eq?(t, cycle) => newCycle
      eqMember?(t, cycleList) => copyCycle2(t, cycleList)
      tree(value t,
           [copyCycle4(c, cycle, newCycle, cycleList) for c in children t])

    -----> cyclicEntries
    cyclicEntries3: (%, List %, List %) -> List %

    cyclicEntries(t) == cyclicEntries3(t, empty()$(List %), empty()$(List %))

    cyclicEntries3(t, parents, cl) ==
      empty? t => cl
      eqMember?(t, parents) => insert(t, cl)
      parents := cons(t, parents)
      for y in children t repeat
        cl := cyclicEntries3(t, parents, cl)
      cl
   
    -----> cyclicEqual?
    cyclicEqual4?: (%, %, List %, List %) -> Boolean

    cyclicEqual?(t1, t2) ==
      cp1 := cyclicParents t1
      cp2 := cyclicParents t2
      #cp1 ~= #cp2 or null cp1 => t1 = t2
      cyclicEqual4?(t1, t2, cp1, cp2)

    cyclicEqual4?(t1, t2, cp1, cp2) == 
      t1 case empty => t2 case empty
      t2 case empty => false
      0 ~= (k := eqMemberIndex(t1, cp1, 0)) => eq?(t2, cp2 . k)
      value t1 = value t2 and 
        "and"/[cyclicEqual4?(x,y,cp1,cp2) 
                 for x in children t1 for y in children t2]

    -----> cyclicParents t
    cyclicParents3: (%, List %, List %) -> List %

    cyclicParents t == cyclicParents3(t, empty()$(List %), empty()$(List %))

    cyclicParents3(x, parents, pl) ==
      empty? x => pl
      eqMember?(x, parents) => 
        cycleMembers := [y for y in parents while not eq?(x,y)]
        eqUnion(cons(x, cycleMembers), pl)
      parents := cons(x, parents)
      for y in children x repeat 
        pl := cyclicParents3(y, parents, pl)
      pl

    insert(x, l) ==
      eqMember?(x, l) => l
      cons(x, l)

    lastNode l ==
      empty? l => error "empty tree has no last node"
      while not empty? rest l repeat l := rest l
      l

    eqMember?(y,l) ==
      for x in l repeat eq?(x,y) => return true
      false

    eqMemberIndex(x, l, k) ==
      null l => k
      k := k + 1
      eq?(x, first l) => k
      eqMemberIndex(x, rest l, k)

    eqUnion(u, v) ==
      null u => v
      x := first u
      newV :=
        eqMember?(x, v) => v
        cons(x, v)
      eqUnion(rest u, newV)

@
\section{category BTCAT BinaryTreeCategory}
<<category BTCAT BinaryTreeCategory>>=
)abbrev category BTCAT BinaryTreeCategory
++ Author:W. H. Burge
++ Date Created:17 Feb 1992
++ Date Last Updated:
++ Basic Operations:
++ Related Domains:
++ Also See:
++ AMS Classifications:
++ Keywords:
++ Examples:
++ References:
++ Description: \spadtype{BinaryTreeCategory(S)} is the category of
++ binary trees: a tree which is either empty or else is a \spadfun{node} consisting
++ of a value and a \spadfun{left} and \spadfun{right}, both binary trees. 
BinaryTreeCategory(S: SetCategory): Category == Join(BinaryRecursiveAggregate S,FiniteAggregate S,ShallowlyMutableAggregate S) with
   node: (%,S,%) -> %
     ++ node(left,v,right) creates a binary tree with value \spad{v}, a binary
     ++ tree \spad{left}, and a binary tree \spad{right}.
 add
     cycleTreeMax ==> 5

     copy t ==
       empty? t => empty()
       node(copy left t, value t, copy right t)
     map!(f,t) ==
       empty? t => t
       t.value := f(t.value)
       map!(f,left t)
       map!(f,right t)
       t
     treeCount : (%, NonNegativeInteger) -> NonNegativeInteger
     #t == treeCount(t,0)
     treeCount(t,k) ==
       empty? t => k
       k := k + 1
       k = cycleTreeMax and cyclic? t => error "cyclic binary tree"
       k := treeCount(left t,k)
       treeCount(right t,k)

@
\section{domain BTREE BinaryTree}
<<domain BTREE BinaryTree>>=
)abbrev domain BTREE BinaryTree
++ Description: \spadtype{BinaryTree(S)} is the domain of all
++ binary trees. A binary tree over \spad{S} is either empty or has
++ a \spadfun{value} which is an S and a \spadfun{right}
++ and \spadfun{left} which are both binary trees.
BinaryTree(S: SetCategory): Exports == Implementation where
  Exports == BinaryTreeCategory(S) with
     binaryTree: S -> %
       ++ binaryTree(v) is an non-empty binary tree
       ++ with value v, and left and right empty.
     binaryTree: (%,S,%) -> %    
       ++ binaryTree(l,v,r) creates a binary tree with
       ++ value v with left subtree l and right subtree r.
  Implementation == add
     Rep := List Tree S
     t1 = t2 == (t1::Rep) =$Rep (t2::Rep)
     empty()== [] pretend %
     node(l,v,r) == cons(tree(v,l:Rep),r:Rep)
     binaryTree(l,v,r) == node(l,v,r)
     binaryTree(v:S) == node(empty(),v,empty())
     empty? t == empty?(t)$Rep
     leaf? t  == empty? t or empty? left t and empty? right t
     right t ==
       empty? t => error "binaryTree:no right"
       rest t
     left t ==
       empty? t => error "binaryTree:no left"
       children first t
     value t==
       empty? t => error "binaryTree:no value"
       value first t
     setvalue! (t,nd)==
       empty? t => error "binaryTree:no value to set"
       setvalue!(first(t:Rep),nd)
       nd
     setleft!(t1,t2) ==
       empty? t1 => error "binaryTree:no left to set"
       setchildren!(first(t1:Rep),t2:Rep)
       t1
     setright!(t1,t2) ==
       empty? t1 => error "binaryTree:no right to set"
       setrest!(t1:List Tree S,t2)

@
\section{domain BSTREE BinarySearchTree}
<<domain BSTREE BinarySearchTree>>=
)abbrev domain BSTREE BinarySearchTree
++ Description: BinarySearchTree(S) is the domain of
++ a binary trees where elements are ordered across the tree.
++ A binary search tree is either empty or has
++ a value which is an S, and a
++ right and left which are both BinaryTree(S)
++ Elements are ordered across the tree.
BinarySearchTree(S: OrderedSet): Exports == Implementation where
  Exports == BinaryTreeCategory(S) with
    binarySearchTree: List S -> %
	++ binarySearchTree(l) \undocumented
    insert!: (S,%) -> %
      ++ insert!(x,b) inserts element x as leaves into binary search tree b.
    insertRoot!: (S,%) -> %
      ++ insertRoot!(x,b) inserts element x as a root of binary search tree b.
    split:      (S,%) -> Record(less: %, greater: %)
      ++ split(x,b) splits binary tree b into two trees, one with elements greater
      ++ than x, the other with elements less than x.
  Implementation == BinaryTree(S) add
    Rep := BinaryTree(S)
    binarySearchTree(u:List S) ==
      null u => empty()
      tree := binaryTree(first u)
      for x in rest u repeat insert!(x,tree)
      tree
    insert!(x,t) ==
      empty? t => binaryTree(x)
      x >= value t =>
        setright!(t,insert!(x,right t))
        t
      setleft!(t,insert!(x,left t))
      t
    split(x,t) ==
      empty? t => [empty(),empty()]
      x > value t =>
        a := split(x,right t)
        [node(left t, value t, a.less), a.greater]
      a := split(x,left t)
      [a.less, node(a.greater, value t, right t)]
    insertRoot!(x,t) ==
      a := split(x,t)
      node(a.less, x, a.greater)

@
\section{domain BTOURN BinaryTournament}
<<domain BTOURN BinaryTournament>>=
)abbrev domain BTOURN BinaryTournament
++ Description: \spadtype{BinaryTournament(S)} is the domain of
++ binary trees where elements are ordered down the tree.
++ A binary search tree is either empty or is a node containing a
++ \spadfun{value} of type \spad{S}, and a \spadfun{right}
++ and a \spadfun{left} which are both \spadtype{BinaryTree(S)}
BinaryTournament(S: OrderedSet): Exports == Implementation where
  Exports == BinaryTreeCategory(S) with
    binaryTournament: List S -> %
      ++ binaryTournament(ls) creates a binary tournament with the
      ++ elements of ls as values at the nodes.
    insert!: (S,%) -> %
      ++ insert!(x,b) inserts element x as leaves into binary tournament b.
  Implementation == BinaryTree(S) add
    Rep := BinaryTree(S)
    binaryTournament(u:List S) ==
      null u => empty()
      tree := binaryTree(first u)
      for x in rest u repeat insert!(x,tree)
      tree
    insert!(x,t) ==
      empty? t => binaryTree(x)
      x > value t =>
        setleft!(t,copy t)
        setvalue!(t,x)
        setright!(t,empty())
      setright!(t,insert!(x,right t))
      t

@
\section{domain BBTREE BalancedBinaryTree}
<<domain BBTREE BalancedBinaryTree>>=
)abbrev domain BBTREE BalancedBinaryTree
++ Description: \spadtype{BalancedBinaryTree(S)} is the domain of balanced
++ binary trees (bbtree). A balanced binary tree of \spad{2**k} leaves,
++ for some \spad{k > 0}, is symmetric, that is, the left and right
++ subtree of each interior node have identical shape.
++ In general, the left and right subtree of a given node can differ
++ by at most leaf node.
BalancedBinaryTree(S: SetCategory): Exports == Implementation where
  Exports == BinaryTreeCategory(S) with
--  BUG: applies wrong fnct for balancedBinaryTree(0,[1,2,3,4])
--    balancedBinaryTree: (S, List S) -> %
--      ++ balancedBinaryTree(s, ls) creates a balanced binary tree with
--      ++ s at the interior nodes and elements of ls at the
--      ++ leaves.
    balancedBinaryTree: (NonNegativeInteger, S) -> %
      ++ balancedBinaryTree(n, s) creates a balanced binary tree with
      ++ n nodes each with value s.
    setleaves!: (%, List S) -> %
      ++ setleaves!(t, ls) sets the leaves of t in left-to-right order
      ++ to the elements of ls.
    mapUp!: (%, (S,S) -> S) -> S
      ++ mapUp!(t,f) traverses balanced binary tree t in an "endorder"
      ++ (left then right then node) fashion returning t with the value
      ++ at each successive interior node of t replaced by
      ++ f(l,r) where l and r are the values at the immediate
      ++ left and right nodes.
    mapUp!: (%, %, (S,S,S,S) -> S) -> %
      ++ mapUp!(t,t1,f) traverses t in an "endorder" (left then right then node)
      ++ fashion  returning t with the value at each successive interior
      ++ node of t replaced by
      ++ f(l,r,l1,r1) where l and r are the values at the immediate
      ++ left and right nodes. Values l1 and r1 are values at the
      ++ corresponding nodes of a balanced binary tree t1, of identical
      ++ shape at t.
    mapDown!: (%,S,(S,S) -> S) -> %
      ++ mapDown!(t,p,f) returns t after traversing t in "preorder"
      ++ (node then left then right) fashion replacing the successive
      ++ interior nodes as follows. The root value x is
      ++ replaced by q := f(p,x). The mapDown!(l,q,f) and
      ++ mapDown!(r,q,f) are evaluated for the left and right subtrees
      ++ l and r of t.
    mapDown!: (%,S, (S,S,S) -> List S) -> %
      ++ mapDown!(t,p,f) returns t after traversing t in "preorder"
      ++ (node then left then right) fashion replacing the successive
      ++ interior nodes as follows. Let l and r denote the left and
      ++ right subtrees of t. The root value x of t is replaced by p.
      ++ Then f(value l, value r, p), where l and r denote the left
      ++ and right subtrees of t, is evaluated producing two values
      ++ pl and pr. Then \spad{mapDown!(l,pl,f)} and \spad{mapDown!(l,pr,f)}
      ++ are evaluated.
  Implementation == BinaryTree(S) add
    Rep := BinaryTree(S)
    leaf? x ==
      empty? x => false
      empty? left x and empty? right x
--    balancedBinaryTree(x: S, u: List S) ==
--      n := #u
--      n = 0 => empty()
--      setleaves!(balancedBinaryTree(n, x), u)
    setleaves!(t, u) ==
      n := #u
      n = 0 =>
        empty? t => t
        error "the tree and list must have the same number of elements"
      n = 1 =>
        setvalue!(t,first u)
        t
      m := n quo 2
      acc := empty()$(List S)
      for i in 1..m repeat
        acc := [first u,:acc]
        u := rest u
      setleaves!(left t, reverse! acc)
      setleaves!(right t, u)
      t
    balancedBinaryTree(n: NonNegativeInteger, val: S) ==
      n = 0 => empty()
      n = 1 => node(empty(),val,empty())
      m := n quo 2
      node(balancedBinaryTree(m, val), val,
           balancedBinaryTree((n - m) pretend NonNegativeInteger, val))
    mapUp!(x,fn) ==
      empty? x => error "mapUp! called on a null tree"
      leaf? x  => x.value
      x.value := fn(mapUp!(x.left,fn),mapUp!(x.right,fn))
    mapUp!(x,y,fn) ==
      empty? x  => error "mapUp! is called on a null tree"
      leaf? x  =>
        leaf? y => x
        error "balanced binary trees are incompatible"
      leaf? y  =>  error "balanced binary trees are incompatible"
      mapUp!(x.left,y.left,fn)
      mapUp!(x.right,y.right,fn)
      x.value := fn(x.left.value,x.right.value,y.left.value,y.right.value)
      x
    mapDown!(x: %, p: S, fn: (S,S) -> S ) ==
      empty? x => x
      x.value := fn(p, x.value)
      mapDown!(x.left, x.value, fn)
      mapDown!(x.right, x.value, fn)
      x
    mapDown!(x: %, p: S, fn: (S,S,S) -> List S) ==
      empty? x => x
      x.value := p
      leaf? x => x
      u := fn(x.left.value, x.right.value, p)
      mapDown!(x.left, u.1, fn)
      mapDown!(x.right, u.2, fn)
      x

@
\section{domain PENDTREE PendantTree}
<<domain PENDTREE PendantTree>>=
)abbrev domain PENDTREE PendantTree
++ A PendantTree(S)is either a leaf? and is an S or has
++ a left and a right both PendantTree(S)'s
PendantTree(S: SetCategory): T == C where
 T == Join(BinaryRecursiveAggregate(S),CoercibleTo Tree S) with
     ptree : S->%
       ++ ptree(s) is a leaf? pendant tree
     ptree:(%, %)->%
	++ ptree(x,y) \undocumented
 
 C == add
     Rep := Tree S
     import Tree S
     coerce (t:%):Tree S == t pretend Tree S
     ptree(n) == tree(n,[])$Rep pretend %
     ptree(l,r) == tree(value(r:Rep)$Rep,cons(l,children(r:Rep)$Rep)):%
     leaf? t == empty?(children(t)$Rep)
     t1=t2 == (t1:Rep) = (t2:Rep)
     left b ==
       leaf? b => error "ptree:no left"
       first(children(b)$Rep)
     right b ==
       leaf? b => error "ptree:no right"
       tree(value(b)$Rep,rest (children(b)$Rep))
     value b ==
       leaf? b => value(b)$Rep
       error "the pendant tree has no value"
     coerce(b:%): OutputForm ==
       leaf? b => value(b)$Rep :: OutputForm
       paren blankSeparate [left b::OutputForm,right b ::OutputForm]

@
\section{License}
<<license>>=
--Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
--All rights reserved.
--
--Redistribution and use in source and binary forms, with or without
--modification, are permitted provided that the following conditions are
--met:
--
--    - Redistributions of source code must retain the above copyright
--      notice, this list of conditions and the following disclaimer.
--
--    - Redistributions in binary form must reproduce the above copyright
--      notice, this list of conditions and the following disclaimer in
--      the documentation and/or other materials provided with the
--      distribution.
--
--    - Neither the name of The Numerical ALgorithms Group Ltd. nor the
--      names of its contributors may be used to endorse or promote products
--      derived from this software without specific prior written permission.
--
--THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
--IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
--TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
--PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
--OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
--EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
--PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
--PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
--LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
--NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
--SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@
<<*>>=
<<license>>
 
<<domain TREE Tree>>
<<category BTCAT BinaryTreeCategory>>
<<domain BTREE BinaryTree>>
<<domain BBTREE BalancedBinaryTree>>
<<domain BSTREE BinarySearchTree>>
<<domain BTOURN BinaryTournament>>
<<domain PENDTREE PendantTree>>
@
\eject
\begin{thebibliography}{99}
\bibitem{1} nothing
\end{thebibliography}
\end{document}