Flash2

type id
type cache_state_ = { invalid, shared, exclusive }
type wait_type = { none, get, getX }

module cache_line = {
   individual wait : wait_type
   relation invmarked
   individual state_ : cache_state_
}

module header = {
  relation pending
  relation local_
  relation dirty
  relation head
  individual hptr : id
  relation list
  relation real(X:id)
  relation upgrade
  relation shlist(X:id)
}

module network = {
  relation get(S:id,D:id)
  relation put(S:id,D:id)
  relation getX(S:id,D:id)
  relation putX(S:id,D:id)
  relation nak(S:id,D:id)
  relation fack(S:id,D:id)
  relation shwb(S:id,D:id)
}

module wb_network = {
  individual proc : id
  relation wb
}

individual home : id
instantiate cache(X:id) : cache_line
instantiate dir : header
relation collecting
individual requester : id
instantiate net : network
relation rp_net(X:id)
individual real_owner : id
individual fwd_get : wait_type
instantiate wbnet : wb_network
individual last_WB : id
relation nakc
relation invnet(X:id)
relation invack(X:id)

locals used in actions

individual src : id
individual dst : id

after init {
    cache(X).state_ := invalid;
    cache(X).wait := none;
    cache(X).invmarked := false;
    dir.pending := false;
    dir.dirty := false;
    collecting := false;
    net.get(X,Y) := false;
    net.put(X,Y) := false;
    net.getX(X,Y) := false;
    net.putX(X,Y) := false;
    net.fack(X,Y) := false;
    net.shwb(X,Y) := false;
    net.nak(X,Y) := false;
    dir.list := false;
    dir.head := false;
    dir.shlist(X) := false;
    rp_net(X) := false;
    fwd_get := none;
    wbnet.wb := false;
    real_owner := home;
    invnet(X) := false;
    invack(X) := false;
    nakc := false
}

action pi_Local_Get_dirty = {
    assume cache(home).state_ = invalid;
    assume cache(home).wait = none;
    assume ~dir.pending;
    assume dir.dirty;
    dir.pending := true;
    collecting := false;
    cache(home).wait := get;
    net.get(home,dir.hptr) := true;
    requester := home
}

action pi_Local_Get = {
    assume cache(home).state_ = invalid;
    assume cache(home).wait = none;
    assume ~dir.pending;
    assume ~dir.dirty;
    assume ~cache(home).invmarked;
    dir.local_ := true;
    cache(home).state_ := shared
}

TODO: can this ever happen?

action pi_Local_Get_im = {
    assume cache(home).state_ = invalid;
    assume cache(home).wait = none;
    assume ~dir.pending;
    assume ~dir.dirty;
    assume cache(home).invmarked;
    cache(home).invmarked := false
}

action pi_Remote_Get = {
    assume src ~= home;
    assume cache(src).state_ = invalid;
    assume cache(src).wait = none;
    cache(src).wait := get;
    net.get(src,home) := true;
    src := *
}

action ni_Local_Get_nak = { assume net.get(src,home); assume home ~= src; assume ~rp_net(src); assume dir.pending | (dir.dirty & dir.local_ & cache(home).state_~=exclusive) | (dir.dirty & ~dir.local_ & src = dir.hptr); net.get(src,home) := false; net.nak(home,src) := true }

action ni_Local_Get = { assume net.get(src,home); assume home ~= src; assume ~dir.pending & ~dir.dirty & ~ rp_net(src) & ~cache(src).invmarked; net.get(src,home) := false; net.put(home,src) := true; if (dir.head) { dir.list := true; dir.shlist(src) := true; dir.real := dir.shlist # what is this? } else { dir.head := true; dir.hptr := src } }

action ni_Local_Get = {
    assume net.get(src,home);
    assume home ~= src;
    assume ~dir.pending & ~dir.dirty & ~ rp_net(src) & ~cache(src).invmarked;
    net.get(src,home) := false;
    net.put(home,src) := true;
    dir.head := true;
    dir.hptr := src;
    dir.shlist(src) := true;
    src := *
}

action ni_Local_Get_fwd = {
    assume net.get(src,home);
    assume home ~= src;
    assume ~dir.pending & dir.dirty & ~dir.local_ & src ~= dir.hptr;
    net.get(src,home) := false;
    dir.pending := true;
    net.get(src,dir.hptr) := true;
    src := *
}

action ni_Remote_Put = {
    assume dst ~= home;
    assume net.put(src,dst);
    net.put(src,dst) := false;
    cache(dst).wait := none;
    cache(dst).state_ := shared;
    src := *;
    dst := *
}

Non-deterministically drop a shared line from the cache. Send an rp message. informing the directory.

action pi_Remote_Replace = {
    assume cache(src).state_=shared & cache(src).wait=none & src ~= home;
    cache(src).state_ := invalid;
    rp_net(src) := true;
    src := *
}

Directory receives a replace message, removes sender from sharing list, assuming it is not head.

action ni_Replace_list = {
    assume rp_net(src);
    assume dir.hptr ~= src;
    rp_net(src) := false;
    dir.shlist(src) := false;
    dir.real(src) := false;
    src := *
}

Remote is invalid and wants an exclusive copy

action pi_Remote_GetX = {
    assume cache(src).state_=invalid & cache(src).wait=none & src ~= home;
    cache(src).wait := getX;
    net.getX(src,home) := true;
    src := *
}

Directory receives an exclusive request. This action handles the case when no invalidation is needed, that is, there is no exclusive copy and either the sharing list is empty or it contains only the source.

action ni_Local_GetX = {
    assume net.getX(src,home);
    assume home ~= src;
    assume ~dir.pending & ~dir.dirty;
    assume ~dir.head | src = dir.hptr;
    assume ~dir.head | ~dir.shlist(X) | X = src;
    net.getX(src,home) := false;
    dir.dirty := true;
    dir.head := true;
    dir.hptr := src;
    dir.real(X) := X = src;
    dir.shlist(X) := X = src;
    net.putX(home,src) := true;
    real_owner := src; # ghost
    cache(home).state_ := invalid;
    cache(home).invmarked := (cache(home).wait = get & dir.local_) | cache(home).invmarked;
    src := *
}

Directory receives an exclusive request. This action handles the case when the request is nak'd

action ni_Local_GetX_nak = {
    assume net.getX(src,home);
    assume home ~= src;
    assume dir.pending | dir.dirty & cache(home).state_ ~= exclusive | src = dir.hptr;
    net.getX(src,home) := false;
    net.nak(home,src) := true;
    src := *
}

Directory receives an exclusive request. This action handles the case when the request is pended.

action ni_Local_GetX_pend = {
    assume net.getX(src,home);
    assume home ~= src;
    assume ~dir.pending & dir.dirty & ~dir.local_ & src ~= dir.hptr;
    net.getX(src,home) := false;
    dir.pending :=  true;
    collecting := false;
    net.getX(src,dir.hptr) := true;
    fwd_get := getX;
    requester := src;
    src := *
}

Directory receives an exclusive request. This action handles the case when invalidations are sent out.

action ni_localGetX_inv = {
    assume net.getX(src,home);
    assume home ~= src;
    assume ~dir.pending & ~dir.dirty & ~dir.local_;
    assume dir.head;
    assume src ~= dir.hptr | (dir.shlist(dst) & dst~=src);
    net.getX(src,home) := false;
    invnet(X) := X ~= home & X ~= src & dir.shlist(X);
    collecting := true;

m1 := m; last_other_invack := (dir.hptr ~= src) ? dir.hptr . {i . i in Proc, dir.shlist(i) & i~=src};

    cache(home).invmarked := (cache(home).wait = get & dir.local_) | cache(home).invmarked;
    dir.local_ := false;
    dir.dirty := true;
    dir.head := true;
    dir.hptr := src;
    dir.pending := true;
    dir.real(X) := X ~= home & X ~= src & dir.shlist(X);
    dir.shlist(X) := X = src;
    net.putX(home,src) := true;
    real_owner := src;
    cache(home).state_ := invalid;
    src := *;
    dst := *
}

action ni_Remote_PutX = {
    assume net.putX(src,dst);
    assume dst~=home & cache(dst).wait = getX;
    net.putX(src,dst) := false;
    cache(dst).wait :=none;
    cache(dst).invmarked := false;
    cache(dst).state_ :=exclusive;
    src := *;
    dst := *
}

action pi_Remote_PutX = {
    assume cache(src).state_ = exclusive & src ~= home; # cache(src).wait=none ???
    cache(src).state_ := invalid;
    wbnet.proc := src;
    wbnet.wb := true;
    src := *
}

action ni_Inv = {
    assume invnet(dst) & dst~=home;
    invnet(dst) := false;
    invack(dst) := true;
    cache(dst).invmarked := (cache(dst).wait = get) | cache(dst).invmarked;
    cache(dst).state_ := invalid;
    dst := *
}

action ni_InvAck = {
      assume dir.pending & invack(src) & src~=home;
      assume dir.real(dst) & dst ~= src;
      invack(src) := false;
      dir.real(src) := false;

last_invack := src; last_other_invack := {i : i in Proc, dir.real(i) & i ~= src};

      src := *;
      dst := *
}

action ni_InvAck_last = {
    assume dir.pending & invack(src) & src~=home;
    assume ~dir.real(X) | X = src;
    dir.pending := false;
    collecting := false;

m1 := undefined; ???

    invack(src) := false;
    dir.real(src) := false;

last_invack := src;

    if ( dir.local_ & ~ dir.dirty)  {
       dir.local_ := false
    }
}


action ni_WB = {
    assume wbnet.wb;
    wbnet.wb := false;
    dir.dirty := false;
    dir.head := false;
    dir.shlist(X) := false;
    last_WB := wbnet.proc
}

action ni_Remote_GetX_nak = {
  assume net.getX(src,dst);
  assume dst ~=src & dst ~= home & cache(dst).state_ ~= exclusive;
  net.getX(src,dst) := false;
  fwd_get := none;

fwd_src := src;

  nakc := true;
  net.nak(dst,src) := true;
  src := *;
  dst := *
}

action ni_Remote_GetX_fwd = {
  assume net.getX(src,dst);
  assume dst ~=src & dst ~= home & cache(dst).state_ = exclusive;
  net.getX(src,dst) := false;
  cache(dst).state_ := invalid;
  fwd_get := none;

fwd_src := src;

  net.putX(dst,src) := true;
  real_owner := src;
  if src~=home {
    net.fack(src,home) := true
  };
  src := *;
  dst := *
}

action ni_FAck = {
  assume net.fack(src,home);
  net.fack(src,home) := false;
  dir.pending := false;
  if dir.dirty {
    dir.hptr := src;
    dir.shlist(X) := X = src
 };
 src := *
}

action ni_Remote_Get_nak = {
  assume net.get(src,dst);
  assume dst ~=src & dst ~= home & cache(dst).state_ ~= exclusive;
  net.get(src,dst) := false;
  fwd_get := none;

fwd_src := src;

  nakc := true;
  net.nak(dst,src) := true;
  src := *;
  dst := *
}

action ni_Remote_Get_fwd = {
  assume net.get(src,dst);
  assume dst ~=src & dst ~= home & cache(dst).state_ = exclusive;
  net.get(src,dst) := false;

assume ~cache(src).invmarked; TODO: ???

  cache(dst).state_ := shared;
  fwd_get := none;

fwd_src := src;

  net.put(dst,src) := true;
  if src~=home {
    real_owner := home;
    net.shwb(src,home) := true
  };

shwb_src := dst;

  src := *;
  dst := *
}

action ni_ShWB = {
  assume net.shwb(src,home);
  net.shwb(src,home) := false;
  dir.pending := false;
  dir.dirty := false;
  dir.shlist(src) := true;
  dir.real(X) := dir.shlist(X);

last_WB := shwb_src;

  src := *
}

action ni_NAK_Clear = {
  assume nakc;
  dir.pending := false;
  nakc := false
}

export pi_Local_Get_dirty
export pi_Local_Get
export pi_Local_Get_im
export pi_Remote_Get

export ni_Local_Get_nak export ni_Local_Get

export ni_Local_Get
export ni_Local_Get_fwd
export ni_Remote_Put
export pi_Remote_Replace
export ni_Replace_list
export pi_Remote_GetX
export ni_Local_GetX
export ni_Local_GetX_nak
export ni_Local_GetX_pend
export ni_localGetX_inv
export ni_Remote_PutX
export pi_Remote_PutX
export ni_Inv
export ni_InvAck
export ni_InvAck_last
export ni_WB
export ni_Remote_GetX_nak
export ni_Remote_GetX_fwd
export ni_FAck
export ni_Remote_Get_nak
export ni_Remote_Get_fwd
export ni_ShWB
export ni_NAK_Clear

conjecture [coherent]
  ~(cache(X).state_ = exclusive & cache(X).wait = none &
    cache(Y).state_ = exclusive & cache(Y).wait = none &
    X ~= Y)


invariant [aux]
((Y = Z | ~net.put(Y,X) | ~net.put(Z,X)) &
 (Y = Z | ~net.get(X,Y) | ~net.get(X,Z)) &
 (Y = Z | ~net.putX(Y,X) | ~net.putX(Z,X)) &
 (Y = Z | ~net.getX(X,Y) | ~net.getX(X,Z)) &
 (~net.get(X,Z) | ~net.put(Y,X)) &
 (~net.getX(X,Z) | ~net.putX(Y,X)) &
 ~net.getX(home,Y) &
 (dir.shlist(dir.hptr) | ~dir.head) &
 (cache.wait(X) = get | ~net.get(X,home)) &
 (cache.wait(X) = get | ~net.put(home,X)) &
 (~net.put(home,X) | ~rp_net(X)) &
 (cache.state_(X) ~= exclusive | cache.wait(X) ~= getX) &
 (cache.wait(X) = getX | ~net.getX(X,home)) &
 (cache.wait(X) = getX | ~net.putX(home,X)) &
 (~net.getX(V1,V0) | cache.wait(V1) ~= none) &
 (Y = home | ~net.shwb(X,Y)) &
 (cache.state_(V0) = invalid | ~net.get(V0,V1)) &
 (cache.state_(V0) = invalid | ~net.put(V1,V0)) &
 (cache.wait(V0) = get | ~net.get(V0,V1)) &
 (cache.wait(V0) = get | ~net.put(V1,V0)) &
 (cache.wait(V0) = getX | ~net.getX(V0,V1)) &
 (cache.wait(V0) = getX | ~net.putX(V1,V0)) &
 (V1 = home | ~net.fack(V0,V1)))


invariant (cache.state_(V0) = invalid | ~net.get(V0,V1))
invariant (cache.state_(V0) = invalid | ~net.put(V1,V0))
invariant (cache.state_(X) ~= exclusive | cache.wait(X) ~= getX)
invariant (cache.state_(X) ~= exclusive | dir.head)
invariant (cache.state_(X) = invalid | ~invack(X))
invariant (cache.state_(X) ~= shared | cache.wait(X) ~= get)
invariant cache.wait(real_owner) ~= get
invariant (cache.wait(V0) = get | ~net.get(V0,V1))
invariant (cache.wait(V0) = get | ~net.put(V1,V0))
invariant (cache.wait(V0) = getX | ~net.getX(V0,V1))
invariant (cache.wait(V0) = getX | ~net.putX(V1,V0))
invariant (cache.wait(X) = get | ~net.get(X,home))
invariant (cache.wait(X) = get | ~net.put(home,X))
invariant (cache.wait(X) = getX | ~net.getX(X,home))
invariant (cache.wait(X) = getX | ~net.putX(home,X))
invariant (dir.hptr = real_owner | ~dir.dirty | dir.pending)
invariant (dir.hptr = real_owner | ~net.putX(home,X))
invariant (dir.real(X) | X = real_owner | cache.state_(X) = invalid)
invariant (dir.shlist(dir.hptr) | ~dir.head)
invariant (dir.shlist(V0) | V0 = requester | cache.state_(V0) ~= exclusive)
invariant (dir.shlist(V1) | V1 = home | ~net.put(V0,V1))
invariant (dir.shlist(X) | cache.state_(X) ~= exclusive)
invariant (~dir.shlist(X) | dir.head)
invariant (~dir.shlist(X) | ~net.get(X,home))
invariant (dir.shlist(X) | ~net.put(home,X))
invariant (dir.shlist(X) | ~net.putX(home,X))
invariant (dir.shlist(Y) | ~net.put(X,Y))
invariant (dir.shlist(Y) | ~net.put(X,Y) | dir.dirty)
invariant (dir.shlist(Y) | ~net.put(X,Y) | dir.pending)
invariant (~invack(V0) | cache.state_(V0) ~= shared)
invariant (~invack(X) | ~invnet(X))
invariant ~net.fack(requester,home)
invariant ~net.get(home,Y)
invariant ~net.getX(home,Y)
invariant (~net.getX(V1,V0) | cache.wait(V1) ~= none)
invariant (~net.getX(X,Z) | ~net.putX(Y,X))
invariant (~net.get(X,Z) | ~net.put(Y,X))
invariant ~net.put(dir.hptr,V0)
invariant ~net.put(home,X)
invariant (~net.put(home,X) | ~rp_net(X))
invariant (~net.put(V1,V0) | ~rp_net(V0))
invariant ~net.putX(home,X)
invariant (~net.putX(home,X) | dir.head)
invariant ~net.putX(real_owner,X)
invariant (~net.putX(Y,X) | dir.dirty)
invariant (~net.putX(Y,X) | dir.head)
invariant (~net.put(Y,X) | dir.head)
invariant ~net.shwb(X,home)
invariant (real_owner = Y | ~net.putX(X,Y))
invariant (~rp_net(X) | cache.state_(X) ~= shared)
invariant (V0 = home | ~net.putX(V0,V1))
invariant (V0 = real_owner | cache.state_(V0) ~= shared)
invariant (V1 = home | ~net.fack(V0,V1))
invariant (V1 = V0 | ~net.shwb(V0,home) | ~net.shwb(V1,home))
invariant (X = dir.hptr | cache.state_(X) ~= exclusive)
invariant (X = dir.hptr | ~net.putX(home,X))
invariant (X = real_owner | cache.state_(X) ~= exclusive)
invariant (X = real_owner | ~net.fack(X,Y))
invariant (X = requester | Y = home | ~net.getX(X,Y))
invariant (Y = home | ~net.getX(X,Y))
invariant (Y = home | ~net.getX(X,Y) | dir.dirty)
invariant (Y = home | ~net.getX(X,Y) | dir.head)
invariant (Y = home | ~net.get(X,Y) | dir.dirty)
invariant (Y = home | ~net.get(X,Y) | dir.head)
invariant (Y = home | ~net.putX(Y,X))
invariant (Y = home | ~net.putX(Y,X) | dir.dirty)
invariant (Y = home | ~net.putX(Y,X) | dir.head)
invariant (Y = home | ~net.put(Y,X) | dir.dirty)
invariant (Y = home | ~net.shwb(X,Y))
invariant (Y = home | Y = real_owner | ~net.getX(X,Y))
invariant (Y = home | Y = real_owner | ~net.get(X,Y))
invariant (Y = home | Y = real_owner | ~net.putX(Y,X))
invariant (Y = home | Y = real_owner | ~net.put(Y,X))
invariant (Y = Z | ~net.getX(X,Y) | ~net.getX(X,Z))
invariant (Y = Z | ~net.get(X,Y) | ~net.get(X,Z))
invariant (Y = Z | ~net.putX(Y,X) | ~net.putX(Z,X))
invariant (Y = Z | ~net.put(Y,X) | ~net.put(Z,X))

invariant [net1] ~(net.put(Y,X) & net.put(Z,X) & Y ~= Z) invariant [net2] ~(net.get(X,Y) & net.get(X,Z) & Y ~= Z) invariant [net3] ~(net.putX(Y,X) & net.putX(Z,X) & Y ~= Z) invariant [net4] ~(net.getX(X,Y) & net.getX(X,Z) & Y ~= Z) invariant [net5] ~(net.put(Y,X) & net.get(X,Z)) invariant [net6] ~(net.putX(Y,X) & net.getX(X,Z)) invariant [n1] ~((net.get(X,Y) + net.put(Y,X)) & nh(Y) & Y ~= home) invariant [n2] ~((net.getX(X,Y) + net.putX(Y,X)) & nh(Y) & Y ~= home) invariant [n3] ~(net.get(home,Y) + net.getX(home,Y)) invariant [l1] ₍₍dir.head & dir.shlist(X)) + (dir.head & ~dir.shlist(dir.hptr))) invariant [c2] ~(cache(X).wait = get & cache(X).state_ = shared) invariant [c3] ~((cache(X).wait ~= get + dir.shlist(X)) & net.get(X,home)) invariant [c4] ~((cache(X).wait ~= get + ~dir.shlist(X)) & net.put(home,X)) invariant [c5] ~((cache(X).wait = get + ~dir.shlist(X)) & cache(X).state_ = shared) invariant [c6] ~((cache(X).state_ = shared + ~dir.shlist(X)) & rp_net(X)) invariant [r1] ~(net.put(home,X) & rp_net(X)) invariant [c2x] ~(cache(X).wait = getX & cache(X).state_ = exclusive) invariant [c3x] ~((cache(X).wait ~= getX + dir.shlist(X)) & net.getX(X,home)) invariant [c4x] ~((cache(X).wait ~= getX + ~dir.shlist(X) + X ~= dir.hptr + dir.hptr ~= real_owner) & net.putX(home,X)) invariant [c5x] ~((cache(X).wait = getX + ~dir.shlist(X) + X ~= real_owner) & cache(X).state_ = exclusive) invariant [pe] ~((net.putX(home,X) + cache(X).state_ = exclusive) & (~dir.head + X ~= dir.hptr)) invariant [c6x] ~((cache(X).state_ = exclusive + ~dir.shlist(wbnet.proc)) & wbnet.wb) invariant [r1x] ~((net.putX(home,X) + wbnet.proc ~= dir.hptr + cache(real_owner).state_ ~= invalid) & wbnet.wb) invariant [itp_a] ~(cache.wait(V1) = none & net.getX(V1, V0)) invariant [fa1] ~(net.fack(X,Y) & (X ~= real_owner + X ~= requester)) invariant [itp_b] ~(V0 ~= home & net.putX(V0,V1) & ~dir.pending) invariant [ro1] ~(net.putX(X,Y) & real_owner ~= Y) invariant [itp_c]net.putX(real_owner,X) invariant [misc] ₍dir.pending + dir.pending + ~dir.dirty + dir.dirty) invariant [p1] ₍dir.pending & dir.dirty & dir.hptr ~= real_owner) invariant [shwb1] ~(net.shwb(X,Y) & Y ~= home) invariant [shwb2] ~((net.put(X,Y) + cache(Y).state_ = shared) & ~dir.shlist(Y) & (~net.shwb(Y,home) + ~dir.dirty + ~dir.pending)) invariant [itp_d] ₍V0 = home & net.put(dir.hptr, V0) & ~net.shwb(V0, home)) invariant [itp_e] ₍V1 = home & net.put(V0, V1) & ~net.shwb(V1, home)) invariant [itp_f] ₍V1 = V0 & net.shwb(V0, home) & net.shwb(V1, home)) invariant [itp_g] ₍V1 = home & ~dir.shlist(V1) & net.put(V0, V1)) invariant [itp_h] ~(cache.state_(V0) ~= invalid & (net.get(V0, V1) + net.put(V1,V0))) invariant [ro2] ~((net.get(Y,X) + net.put(X,Y) + net.getX(Y,X)) & real_owner = Y) invariant [ro3] ~(cache(Y).state_ ~= exclusive & cache(Y).wait ~= getX & real_owner = Y) invariant [itp_i] ~(rp_net(V0) & net.put(V1, V0)) invariant [itp_j] ~(cache.wait(V0) ~= get & (net.get(V0, V1) + net.put(V1, V0))) invariant [itp_j2] ~(cache.wait(V0) ~= getX & (net.getX(V0, V1)+ net.putX(V1, V0))) invariant [iv1] ~(invack(X) & (invnet(X) + cache(X).state_ ~= invalid + X = real_owner)) invariant [iv2] ₍dir.real(X) & X ~= real_owner & cache(X).state_ ~= invalid) invariant [itp_k] ₍V0 = real_owner & cache.state_(V0) = shared) invariant [itp_l] ~(invack(V0) & cache.state_(V0) = shared) invariant [itp_m] ₍V1 = home & net.fack(V0, V1)) invariant [itp_n = cache.wait]get invariant [nakc1] ~((nakc + net.fack(requester, home)) & net.getX(X,Y) & Y ~= home) invariant [getx1] ~((net.getX(X,Y) + net.putX(Y,X)) & Y ~= home & X ~= requester) invariant [shwb3] ~(net.shwb(X,home) & cache(Y).state_ = exclusive) invariant [shwb4] ~(net.shwb(X,home) & net.putX(Y,Z)) invariant [itp_o] ~((nakc + ~V0 = requester) & ~dir.shlist(V0) & cache.state_(V0) = exclusive) invariant [nf1] ~(nakc & net.fack(requester,home))