diff --git a/lib/lrama/command.rb b/lib/lrama/command.rb
index 0095c1a1..3ff39d57 100644
--- a/lib/lrama/command.rb
+++ b/lib/lrama/command.rb
@@ -19,7 +19,7 @@ def run(argv)
       text = options.y.read
       options.y.close if options.y != STDIN
       begin
-        grammar = Lrama::Parser.new(text, options.grammar_file, options.debug).parse
+        grammar = Lrama::Parser.new(text, options.grammar_file, options.debug, options.define).parse
         unless grammar.no_stdlib
           stdlib_grammar = Lrama::Parser.new(File.read(STDLIB_FILE_PATH), STDLIB_FILE_PATH, options.debug).parse
           grammar.insert_before_parameterizing_rules(stdlib_grammar.parameterizing_rules)
@@ -34,6 +34,7 @@ def run(argv)
       end
       states = Lrama::States.new(grammar, trace_state: (options.trace_opts[:automaton] || options.trace_opts[:closure]))
       states.compute
+      states.compute_ielr if grammar.ielr_defined?
       context = Lrama::Context.new(states)
 
       if options.report_file
diff --git a/lib/lrama/grammar.rb b/lib/lrama/grammar.rb
index 3724f828..955d47dd 100644
--- a/lib/lrama/grammar.rb
+++ b/lib/lrama/grammar.rb
@@ -28,14 +28,14 @@ class Grammar
     attr_reader :percent_codes, :eof_symbol, :error_symbol, :undef_symbol, :accept_symbol, :aux, :parameterizing_rule_resolver
     attr_accessor :union, :expect, :printers, :error_tokens, :lex_param, :parse_param, :initial_action,
                   :after_shift, :before_reduce, :after_reduce, :after_shift_error_token, :after_pop_stack,
-                  :symbols_resolver, :types, :rules, :rule_builders, :sym_to_rules, :no_stdlib, :locations
+                  :symbols_resolver, :types, :rules, :rule_builders, :sym_to_rules, :no_stdlib, :locations, :define
 
     def_delegators "@symbols_resolver", :symbols, :nterms, :terms, :add_nterm, :add_term,
                                         :find_symbol_by_number!, :find_symbol_by_id!, :token_to_symbol,
                                         :find_symbol_by_s_value!, :fill_symbol_number, :fill_nterm_type,
                                         :fill_printer, :fill_destructor, :fill_error_token, :sort_by_number!
 
-    def initialize(rule_counter)
+    def initialize(rule_counter, define = {})
       @rule_counter = rule_counter
 
       # Code defined by "%code"
@@ -57,6 +57,7 @@ def initialize(rule_counter)
       @aux = Auxiliary.new
       @no_stdlib = false
       @locations = false
+      @define = define
 
       append_special_symbols
     end
@@ -171,6 +172,10 @@ def find_rules_by_symbol(sym)
       @sym_to_rules[sym.number]
     end
 
+    def ielr_defined?
+      @define.key?('lr.type') && @define['lr.type'] == 'ielr'
+    end
+
     private
 
     def compute_nullable
diff --git a/lib/lrama/option_parser.rb b/lib/lrama/option_parser.rb
index 0727d1b3..d6f4b32b 100644
--- a/lib/lrama/option_parser.rb
+++ b/lib/lrama/option_parser.rb
@@ -61,6 +61,7 @@ def parse_by_option_parser(argv)
         o.on('-S', '--skeleton=FILE', 'specify the skeleton to use') {|v| @options.skeleton = v }
         o.on('-t', 'reserved, do nothing') { }
         o.on('--debug', 'display debugging outputs of internal parser') {|v| @options.debug = true }
+        o.on('-D', '--define=NAME[=VALUE]', Array, "similar to '%define NAME VALUE'") {|v| @options.define = v }
         o.separator ''
         o.separator 'Output:'
         o.on('-H', '--header=[FILE]', 'also produce a header file named FILE') {|v| @options.header = true; @options.header_file = v }
diff --git a/lib/lrama/options.rb b/lib/lrama/options.rb
index ccd76803..08f75a77 100644
--- a/lib/lrama/options.rb
+++ b/lib/lrama/options.rb
@@ -7,10 +7,11 @@ class Options
                   :report_file, :outfile,
                   :error_recovery, :grammar_file,
                   :trace_opts, :report_opts,
-                  :diagnostic, :y, :debug
+                  :diagnostic, :y, :debug, :define
 
     def initialize
       @skeleton = "bison/yacc.c"
+      @define = {}
       @header = false
       @header_file = nil
       @report_file = nil
diff --git a/lib/lrama/parser.rb b/lib/lrama/parser.rb
index 6a35dba2..589e3389 100644
--- a/lib/lrama/parser.rb
+++ b/lib/lrama/parser.rb
@@ -658,17 +658,18 @@ class Parser < Racc::Parser
 
 include Lrama::Report::Duration
 
-def initialize(text, path, debug = false)
+def initialize(text, path, debug = false, define = {})
   @grammar_file = Lrama::Lexer::GrammarFile.new(path, text)
   @yydebug = debug
   @rule_counter = Lrama::Grammar::Counter.new(0)
   @midrule_action_counter = Lrama::Grammar::Counter.new(1)
+  @define = define
 end
 
 def parse
   report_duration(:parse) do
     @lexer = Lrama::Lexer.new(@grammar_file)
-    @grammar = Lrama::Grammar.new(@rule_counter)
+    @grammar = Lrama::Grammar.new(@rule_counter, @define)
     @precedence_number = 0
     reset_precs
     do_parse
@@ -906,7 +907,7 @@ def raise_parse_error(error_message, location)
   2, 71, :_reduce_15,
   1, 58, :_reduce_none,
   2, 58, :_reduce_17,
-  3, 58, :_reduce_none,
+  3, 58, :_reduce_18,
   2, 58, :_reduce_none,
   2, 58, :_reduce_20,
   2, 58, :_reduce_21,
@@ -1313,7 +1314,12 @@ def _reduce_17(val, _values, result)
   end
 .,.,
 
-# reduce 18 omitted
+module_eval(<<'.,.,', 'parser.y', 27)
+  def _reduce_18(val, _values, result)
+     @grammar.define[val[1].s_value] = val[2]&.s_value
+    result
+  end
+.,.,
 
 # reduce 19 omitted
 
diff --git a/lib/lrama/state.rb b/lib/lrama/state.rb
index c2623746..5123d136 100644
--- a/lib/lrama/state.rb
+++ b/lib/lrama/state.rb
@@ -5,12 +5,13 @@
 require_relative "state/resolved_conflict"
 require_relative "state/shift"
 require_relative "state/shift_reduce_conflict"
+require_relative "state/inadequacy_annotation"
 
 module Lrama
   class State
     attr_reader :id, :accessing_symbol, :kernels, :conflicts, :resolved_conflicts,
-                :default_reduction_rule, :closure, :items
-    attr_accessor :shifts, :reduces
+                :default_reduction_rule, :closure, :items, :predecessors
+    attr_accessor :shifts, :reduces, :lalr_isocore
 
     def initialize(id, accessing_symbol, kernels)
       @id = id
@@ -23,6 +24,8 @@ def initialize(id, accessing_symbol, kernels)
       @conflicts = []
       @resolved_conflicts = []
       @default_reduction_rule = nil
+      @predecessors = []
+      @lalr_isocore = self
     end
 
     def closure=(closure)
@@ -84,6 +87,11 @@ def transitions
       @transitions ||= shifts.map {|shift| [shift, @items_to_state[shift.next_items]] }
     end
 
+    def update_transition(shift, next_state)
+      set_items_to_state(shift.next_items, next_state)
+      @transitions = shifts.map {|sh| [sh, @items_to_state[sh.next_items]] }
+    end
+
     def selected_term_transitions
       term_transitions.reject do |shift, next_state|
         shift.not_selected
@@ -142,5 +150,175 @@ def rr_conflicts
         conflict.type == :reduce_reduce
       end
     end
+
+    def always_follows(shift, next_state)
+      internal_dependencies(shift, next_state).union(successor_dependencies(shift, next_state)).reduce([]) {|result, transition| result += transition[1].term_transitions.map {|shift, _| shift.next_sym } }
+    end
+
+    def internal_dependencies(shift, next_state)
+      nterm_transitions.select {|other_shift, _|
+        @items.find {|item| item.next_sym == shift.next_sym && item.lhs == other_shift.next_sym && item.symbols_after_dot.all?(&:nullable) }
+      }.reduce([[shift, next_state]]) {|result, transition|
+        result += internal_dependencies(*transition)
+      }
+    end
+
+    def successor_dependencies(shift, next_state)
+      next_state.nterm_transitions.select {|other_shift, _|
+        other_shift.next_sym.nullable
+      }.reduce([[shift, next_state]]) {|result, transition|
+        result += successor_dependencies(*transition)
+      }
+    end
+
+    def inspect
+      "#{id} -> #{@kernels.map(&:to_s).join(', ')}"
+    end
+
+    def inadequacy_list
+      return @inadequacy_list if @inadequacy_list
+
+      shift_contributions = shifts.to_h {|shift|
+        [shift.next_sym, [shift]]
+      }
+      reduce_contributions = reduces.map {|reduce|
+        (reduce.look_ahead || []).to_h {|sym|
+          [sym, [reduce]]
+        }
+      }.reduce(Hash.new([])) {|hash, cont|
+        hash.merge(cont) {|_, a, b| a.union(b) }
+      }
+
+      list = shift_contributions.merge(reduce_contributions) {|_, a, b| a.union(b) }
+      @inadequacy_list = list.select {|token, actions| token.term? && actions.size > 1 }
+    end
+
+    def annotate_manifestation
+      inadequacy_list.map {|token, actions|
+        actions.map {|action|
+          if action.is_a?(Shift)
+            [InadequacyAnnotation.new(token: token, action: action, item: nil, contributed: false)]
+          elsif action.is_a?(Reduce)
+            if action.rule.empty_rule?
+              lhs_contributions(action.rule.lhs, token).map {|kernel, contributed|
+                InadequacyAnnotation.new(token: token, action: action, item: kernel, contributed: contributed)
+              }
+            else
+              kernels.map {|kernel|
+                contributed = kernel.rule == action.rule && kernel.end_of_rule?
+                InadequacyAnnotation.new(token: token, action: action, item: kernel, contributed: contributed)
+              }
+            end
+          end
+        }
+      }
+    end
+
+    def annotate_predecessor(annotation_list)
+      annotation_list.reduce([]) {|annotation|
+        next [token, {}] if annotation.no_contributions? || actions.any? {|action, hash|
+          p action, hash
+          hash.keys.any? {|item| hash[item] && item.position == 1 && compute_lhs_contributions(state, item.lhs, token).empty? }
+        }
+        [
+          token, actions.to_h {|action, hash|
+            [
+              action, hash.to_h {|item, _|
+                kernel = state.kernels.find {|k| k.rule == item.rule && k.position == item.position - 1 }
+                [kernel,
+                 hash[item] &&
+                 (
+                   !kernel.nil? && (state.item_lookahead_set[kernel].include?(token)) ||
+                   (item.position == 1 && compute_lhs_contributions(state, item.lhs, token)[item])
+                 )
+                ]
+              }
+            ]
+          }
+        ]
+      }
+    end
+
+    def item_lookahead_set
+      @item_lookahead_set ||=
+        kernels.to_h {|item|
+          value =
+            if item.position > 1
+              prev_state, prev_item = predecessor_with_item(item)
+              prev_state.item_lookahead_set[prev_item]
+            elsif item.position == 1
+              prev_state = predecessors.find {|p| p.shifts.any? {|shift| shift.next_sym == item.lhs } }
+              shift, next_state = prev_state.nterm_transitions.find {|shift, _| shift.next_sym == item.lhs }
+              prev_state.goto_follows(shift, next_state)
+            else
+              []
+            end
+          [item, value]
+        }
+    end
+
+    def item_lookahead_set=(k)
+      @item_lookahead_set = k
+    end
+
+    def predecessor_with_item(item)
+      predecessors.each do |state|
+        state.kernels.each do |kernel|
+          return [state, kernel] if kernel.rule == item.rule && kernel.position == item.position - 1
+        end
+      end
+    end
+
+    def lhs_contributions(sym, token)
+      shift, next_state = nterm_transitions.find {|sh, _| sh.next_sym == sym }
+      if always_follows(shift, next_state).include?(token)
+        []
+      else
+        kernels.map {|kernel| [kernel, follow_kernel?(kernel) && item_lookahead_set[kernel].include?(token)] }
+      end
+    end
+
+    def follow_kernel?(item)
+      item.symbols_after_dot.all?(&:nullable)
+    end
+
+    def follow_kernel_items(shift, next_state, item)
+      internal_dependencies(shift, next_state).any? {|shift, _| shift.next_sym == item.next_sym } && item.symbols_after_dot.all?(&:nullable)
+    end
+
+    def next_terms
+      shifts.filter_map {|shift| shift.next_sym.term? && shift.next_sym }
+    end
+
+    def append_predecessor(prev_state)
+      @predecessors << prev_state
+      @predecessors.uniq!
+    end
+
+    def goto_follows(shift, next_state)
+      include_dependencies(shift, next_state).reduce([]) {|result, goto|
+        st, sh, next_st = goto
+        result.union(st.always_follows(sh, next_st))
+      }
+    end
+
+    def include_dependencies(shift, next_state)
+      internal = internal_dependencies(shift, next_state).map {|sh, next_st| [self, sh, next_st] }
+      pred = predecessor_dependencies(shift, next_state)
+
+      return internal if pred.empty?
+      dependency = internal.union(pred)
+
+      dependency.reduce(dependency) {|result, goto| result.union(compute_include_dependencies(*goto)) }
+    end
+
+    def predecessor_dependencies(shift, next_state)
+      item = kernels.find {|kernel| kernel.next_sym == shift.next_sym }
+      return [] unless item.symbols_after_transition.all?(&:nullable)
+
+      st = @predecessors.find {|p| p.items.find {|i| i.rule == item.rule && i.position == item.position - 1 } }
+      sh, next_st = s.nterm_transitions.find {|shift, _| shift.next_token == item.lhs }
+      [[s, sh, next_st]]
+    end
   end
 end
diff --git a/lib/lrama/state/inadequacy_annotation.rb b/lib/lrama/state/inadequacy_annotation.rb
new file mode 100644
index 00000000..7a1f518d
--- /dev/null
+++ b/lib/lrama/state/inadequacy_annotation.rb
@@ -0,0 +1,9 @@
+module Lrama
+  class State
+    class InadequacyAnnotation < Struct.new(:token, :action, :item, :contributed, keyword_init: true)
+      def no_contributions?
+        item.nil? && !contributed
+      end
+    end
+  end
+end
diff --git a/lib/lrama/states.rb b/lib/lrama/states.rb
index 0ed4bff9..ecfd5a86 100644
--- a/lib/lrama/states.rb
+++ b/lib/lrama/states.rb
@@ -92,6 +92,19 @@ def compute
       report_duration(:compute_default_reduction) { compute_default_reduction }
     end
 
+    def compute_ielr
+      report_duration(:compute_predecessors) { compute_predecessors }
+      report_duration(:split_states) { split_states }
+      @states.each {|state| p state, state.transitions, state.item_lookahead_set }
+      report_duration(:compute_direct_read_sets) { compute_direct_read_sets }
+      report_duration(:compute_reads_relation) { compute_reads_relation }
+      report_duration(:compute_read_sets) { compute_read_sets }
+      report_duration(:compute_includes_relation) { compute_includes_relation }
+      report_duration(:compute_lookback_relation) { compute_lookback_relation }
+      report_duration(:compute_follow_sets) { compute_follow_sets }
+      report_duration(:compute_look_ahead_sets) { compute_look_ahead_sets }
+    end
+
     def reporter
       StatesReporter.new(self)
     end
@@ -524,5 +537,136 @@ def compute_default_reduction
         end.first
       end
     end
+
+    def compute_predecessors
+      queue = [@states.first]
+      until queue.empty?
+        state = queue.shift
+        state.transitions.each do |_, next_state|
+          next_state.append_predecessor(state)
+          queue << next_state
+        end
+      end
+    end
+
+    def split_states
+      @ielr_isocores = Hash.new {|hash, key| hash[key] = [key] }
+      @lookaheads_recomputed = Hash.new {|hash, key| hash[key] = false }
+      transition_queue = []
+      @states.first.transitions.each do |shift, next_state|
+        transition_queue << [@states.first, shift, next_state]
+      end
+      until transition_queue.empty?
+        state, shift, next_state = transition_queue.shift
+        compute_state(state, shift, next_state)
+        next_state.transitions.each do |sh, next_st|
+          transition_queue << [next_state, sh, next_st]
+        end
+      end
+    end
+
+    def merge_lookaheads(state, k)
+      return if state.kernels.all? {|item| (k[item] - state.item_lookahead_set[item]).empty? }
+
+      state.transitions.each do |shift, next_state|
+        next if @lookaheads_recomputed[next_state]
+        compute_state(state, shift, next_state)
+      end
+    end
+
+    def compute_state(state, shift, next_state)
+      k = propagate_lookaheads(state, next_state)
+      s = @ielr_isocores[next_state].find {|st| is_compatible(st, k) }
+
+      if s.nil?
+        s = @ielr_isocores[next_state].last
+        new_state = State.new(@states.count, s.accessing_symbol, s.kernels)
+        new_state.closure = s.closure
+        new_state.compute_shifts_reduces
+        s.transitions.each do |sh, next_state|
+          new_state.set_items_to_state(sh.next_items, next_state)
+        end
+        @states << new_state
+        new_state.lalr_isocore = s
+        @ielr_isocores[s] << new_state
+        @ielr_isocores[s].each do |st|
+          @ielr_isocores[st] = @ielr_isocores[s]
+        end
+        @lookaheads_recomputed[new_state] = true
+        new_state.item_lookahead_set = k
+        state.update_transition(shift, new_state)
+      elsif(!@lookaheads_recomputed[s])
+        s.item_lookahead_set = k
+        @lookaheads_recomputed[s] = true
+      else
+        state.update_transition(shift, s)
+        merge_lookaheads(s, k)
+      end
+    end
+
+    def propagate_lookaheads(state, next_state)
+      next_state.kernels.to_h {|item|
+        lookahead_sets =
+          if item.position == 1
+            compute_goto_follow_set(state.lalr_isocore, item.lhs)
+          else
+            kernel = state.kernels.find {|k| k.rule == item.rule && k.position == item.position - 1 }
+            state.item_lookahead_set[kernel]
+          end
+
+        # p [state, lookahead_sets, lookahead_set_filters(next_state)[item]]
+
+        [item, lookahead_sets & lookahead_set_filters(next_state)[item]]
+      }
+    end
+
+    def lookahead_set_filters(state)
+      p state
+      state.kernels.to_h {|kernel|
+        # p [state, kernel, annotation_list(@lalr_isocores[state])]
+        [kernel,
+         annotation_list(state.lalr_isocore).filter_map {|token, actions|
+          token if token.term? && actions.any? {|item, _| item == kernel }
+        }]
+      }
+    end
+
+    def is_compatible(state, k)
+      !@lookaheads_recomputed[state] ||
+        annotation_list(state.lalr_isocores).all? {|token, actions|
+          a = dominant_contribution(state, token, actions, state.item_lookahead_set)
+          b = dominant_contribution(state, token, actions, k)
+          a.empty? || b.empty? || a == b
+        }
+    end
+
+    def dominant_contribution(state, token, actions, lookaheads)
+      actions.filter_map {|action, items|
+        action if items.empty? || items.any? {|item, bool| bool && lookaheads[item].include?(token) }
+      }.reject {|action|
+        if action.is_a?(State::Shift)
+          action.not_selected
+        elsif action.is_a?(State::Reduce)
+          action.not_selected_symbols.include?(token)
+        end
+      }
+    end
+
+    def compute_goto_follow_set(state, nterm_token)
+      shift, next_state = state.nterm_transitions.find {|shift, _| shift.next_sym == nterm_token }
+      return [] if shift.nil? && nterm_token.id.s_value == '$accept'
+      state.always_follows(shift, next_state).union(state.kernels.select {|item|
+        state.follow_kernel_items(shift, next_state, item)
+      }.reduce([]) {|result, item|
+        result.union(state.item_lookahead_set[item])
+      })
+    end
+
+    def annotation_list(state)
+      manifestations = state.annotate_manifestation
+      predecessors = state.transitions.map {|_, next_state| state.annotate_predecessor(annotation_list(next_state)) }
+      p state, state.inadequacy_list, manifestations, predecessors
+      manifestations + predecessors
+    end
   end
 end
diff --git a/lib/lrama/states/item.rb b/lib/lrama/states/item.rb
index 5074e943..08a8df91 100644
--- a/lib/lrama/states/item.rb
+++ b/lib/lrama/states/item.rb
@@ -64,6 +64,10 @@ def symbols_after_dot # steep:ignore
         rhs[position..-1]
       end
 
+      def symbols_after_transition
+        rhs[position+1..-1]
+      end
+
       def to_s
         "#{lhs.id.s_value}: #{display_name}"
       end
diff --git a/parser.y b/parser.y
index 52603a72..cadc4cb6 100644
--- a/parser.y
+++ b/parser.y
@@ -25,7 +25,7 @@ rule
 
   bison_declaration: grammar_declaration
                    | "%expect" INTEGER { @grammar.expect = val[1] }
-                   | "%define" variable value
+                   | "%define" variable value { @grammar.define[val[1].s_value] = val[2]&.s_value }
                    | "%param" param+
                    | "%lex-param" param+
                        {
@@ -417,17 +417,18 @@ end
 
 include Lrama::Report::Duration
 
-def initialize(text, path, debug = false)
+def initialize(text, path, debug = false, define = {})
   @grammar_file = Lrama::Lexer::GrammarFile.new(path, text)
   @yydebug = debug
   @rule_counter = Lrama::Grammar::Counter.new(0)
   @midrule_action_counter = Lrama::Grammar::Counter.new(1)
+  @define = define
 end
 
 def parse
   report_duration(:parse) do
     @lexer = Lrama::Lexer.new(@grammar_file)
-    @grammar = Lrama::Grammar.new(@rule_counter)
+    @grammar = Lrama::Grammar.new(@rule_counter, @define)
     @precedence_number = 0
     reset_precs
     do_parse
diff --git a/sample/calc.y b/sample/calc.y
index b4c4ca30..f9915d87 100644
--- a/sample/calc.y
+++ b/sample/calc.y
@@ -25,6 +25,7 @@ static int yyerror(YYLTYPE *loc, const char *str);
 %union {
     int val;
 }
+%define lr.type ielr
 %token LF
 %token <val> NUM
 %type <val> expr
diff --git a/spec/fixtures/integration/calculator.y b/spec/fixtures/integration/calculator.y
index 54b86b7a..d3ec5c06 100644
--- a/spec/fixtures/integration/calculator.y
+++ b/spec/fixtures/integration/calculator.y
@@ -16,6 +16,7 @@ static int yyerror(YYLTYPE *loc, const char *str);
 %type <val> expr
 %left '+' '-'
 %left '*' '/'
+%define lr.type ielr
 
 %locations
 
diff --git a/spec/fixtures/integration/ielr.y b/spec/fixtures/integration/ielr.y
new file mode 100644
index 00000000..d8680a30
--- /dev/null
+++ b/spec/fixtures/integration/ielr.y
@@ -0,0 +1,62 @@
+%{
+#include <stdio.h>
+#include <stdlib.h>
+#include "y.tab.h"
+#define YYDEBUG 1
+static int yylex(YYSTYPE *val, YYLTYPE *loc);
+static int yyerror(YYLTYPE *loc, const char *str);
+%}
+
+%union {
+    int val;
+}
+
+%token a
+%token b
+%token c
+%define lr.type ielr
+
+%%
+S: a A B a
+ | b A B b
+A: a C D E
+B: c
+ | // empty
+C: D
+D: a
+E: a
+ | // empty
+
+%%
+
+static int yylex(YYSTYPE *yylval, YYLTYPE *loc) {
+    int c = getchar();
+    printf("%c\n", c);
+    int val;
+
+    switch (c) {
+    case ' ': case '\t':
+        return yylex(yylval, loc);
+
+    case 'a': case 'b': case 'c':
+        return c;
+
+    case '\n':
+        exit(0);
+
+    default:
+        fprintf(stderr, "unknown character: %c\n", c);
+        exit(1);
+    }
+}
+
+static int yyerror(YYLTYPE *loc, const char *str) {
+    fprintf(stderr, "parse error: %s\n", str);
+    return 0;
+}
+
+int main() {
+    printf("Enter the formula:\n");
+    yyparse();
+    return 0;
+}
diff --git a/spec/lrama/parser_spec.rb b/spec/lrama/parser_spec.rb
index 8b14ee5f..db6c2205 100644
--- a/spec/lrama/parser_spec.rb
+++ b/spec/lrama/parser_spec.rb
@@ -59,6 +59,7 @@
       CODE
 
       expect(grammar.expect).to eq(0)
+      expect(grammar.define).to eq({'api.pure' => nil, 'parse.error' => 'verbose'})
       expect(grammar.printers).to eq([
         Printer.new(
           ident_or_tags: [T::Tag.new(s_value: "<int>")],
diff --git a/spec/lrama/state_spec.rb b/spec/lrama/state_spec.rb
new file mode 100644
index 00000000..df20b1df
--- /dev/null
+++ b/spec/lrama/state_spec.rb
@@ -0,0 +1,29 @@
+RSpec.describe Lrama::State do
+  let(:grammar) { <<-FILE }
+  %union {
+      int val;
+  }
+
+  %token a
+  %token b
+  %token c
+  %define lr.type ielr
+
+  %%
+  S: a A B a
+   | b A B b
+  A: a C D E
+  B: c
+   | // empty
+  C: D
+  D: a
+  E: a
+   | // empty
+  %%
+  FILE
+
+
+  describe '#internal_dependencies' do
+
+  end
+end
diff --git a/spec/lrama/states_spec.rb b/spec/lrama/states_spec.rb
index 953ac54c..c4d4cf0f 100644
--- a/spec/lrama/states_spec.rb
+++ b/spec/lrama/states_spec.rb
@@ -1787,4 +1787,17 @@ class    go to state 5
       STR
     end
   end
+
+  describe '#compute_ielr' do
+    it 'recompute states' do
+      path = "integration/ielr.y"
+      y = File.read(fixture_path(path))
+      grammar = Lrama::Parser.new(y, path).parse
+      grammar.prepare
+      grammar.validate!
+      states = Lrama::States.new(grammar, warning)
+      states.compute
+      states.compute_ielr
+    end
+  end
 end