Adding Otter theorem prover. The development is frozen, but because of that Otter is considered a very reliable prover from soundness point of view.

pkgs/applications/science/logic/otter/default.nix

···
+{stdenv, fetchurl, tcsh, libXaw, libXt, libX11}:
+let
+  s = # Generated upstream information
+  rec {
+    version = "3.3f";
+    name = "otter";
+    url = "http://www.cs.unm.edu/~mccune/otter/otter-${version}.tar.gz";
+    sha256 = "16mc1npl7sk9cmqhrf3ghfmvx29inijw76f1b1lsykllaxjqqb1r";
+  };
+  buildInputs = [
+    tcsh libXaw libXt libX11
+  ];
+in
+stdenv.mkDerivation {
+  inherit (s) name version;
+  inherit buildInputs;
+  src = fetchurl {
+    inherit (s) url sha256;
+  };
+  buildPhase = ''
+    find . -name Makefile | xargs sed -i -e "s@/bin/rm@$(type -P rm)@g"
+    find . -name Makefile | xargs sed -i -e "s@/bin/mv@$(type -P mv)@g"
+    find . -perm +111 -type f | xargs sed -i -e "s@/bin/csh@$(type -P csh)@g"
+    find . -perm +111 -type f | xargs sed -i -e "s@/bin/rm@$(type -P rm)@g"
+    find . -perm +111 -type f | xargs sed -i -e "s@/bin/mv@$(type -P mv)@g"
+
+    sed -i -e "s/^XLIBS *=.*/XLIBS=-lXaw -lXt -lX11/" source/formed/Makefile 
+
+    make all
+    make -C examples all
+    make -C examples-mace2 all
+    make -C source/formed realclean
+    make -C source/formed formed
+  '';
+  installPhase = ''
+    mkdir -p "$out"/{bin,share/otter}
+    cp bin/* source/formed/formed "$out/bin/"
+    cp -r examples examples-mace2 documents README* Legal Changelog Contents index.html "$out/share/otter/"
+  '';
+  meta = {
+    inherit (s) version;
+    description = "A reliable first-order theorem prover";
+    license = stdenv.lib.licenses.publicDomain ;
+    maintainers = [stdenv.lib.maintainers.raskin];
+    platforms = stdenv.lib.platforms.linux;
+  };
+}

pkgs/top-level/all-packages.nix

···
 
   opensmt = callPackage ../applications/science/logic/opensmt { };
 
+  otter = callPackage ../applications/science/logic/otter {};
+
   picosat = callPackage ../applications/science/logic/picosat {};
 
   prover9 = callPackage ../applications/science/logic/prover9 { };