diff --git a/cell.cpp b/cell.cpp
index a8cbec539de5178c83c44df1de75ea84093d1862..31566fbace49b71ecc28f0460037e76ec00b6633 100644
--- a/cell.cpp
+++ b/cell.cpp
@@ -27,7 +27,7 @@ Cell::Cell(QWidget *parent) : QWidget(parent)
     m_groupBox->setLayout(m_gridLayout);
     m_number = new QPushButton(this);
 
-    connect(m_number, SIGNAL(clicked()), this, SLOT(un()));
+    connect(m_number, SIGNAL(clicked()), this, SLOT(collapsedCellClicked()));
     m_stackedWidget = new QStackedWidget(this);
     m_stackedWidget->addWidget(m_groupBox);
     m_stackedWidget->addWidget(m_number);
@@ -57,7 +57,7 @@ void Cell::removeOption(int x)
         m_states[x]->setText(" ");
         m_states[x]->setDisabled(true);
         possibleStates--;
-        index.erase(std::find(index.begin(), index.end(), x));
+        options.erase(std::find(options.begin(), options.end(), x));
     }
     m_blocked[x]++;
 }
@@ -71,10 +71,10 @@ void Cell::addOption(int x)
         m_states[x]->setText(QString::number(x + 1));
         m_states[x]->setDisabled(false);
         possibleStates++;
-        index.push_back(x);
+        options.push_back(x);
     }
 }
-void Cell::un(void)
+void Cell::collapsedCellClicked(void)
 {
     collapsed = false;
     m_stackedWidget->setCurrentIndex(0);
diff --git a/cell.h b/cell.h
index cf4fcb487a0007921f615dff7ff90c9511e0cb7c..202b246622f844d7b38726cf758b4e149cc47904 100644
--- a/cell.h
+++ b/cell.h
@@ -15,7 +15,7 @@ public:
     void resizeEvent(QResizeEvent *event);
     int possibleStates = 9;
     bool collapsed = false;
-    std::vector<int> index = {0, 1, 2, 3, 4, 5, 6, 7, 8};
+    std::vector<int> options = {0, 1, 2, 3, 4, 5, 6, 7, 8};
 
 private:
     QSignalMapper *m_mapper;
@@ -33,7 +33,7 @@ public slots:
     void addOption(int x);
     void removeOption(int x);
     void collapse(int x);
-    void un(void);
+    void collapsedCellClicked(void);
 };
 
 #endif // CELL_H
\ No newline at end of file
diff --git a/window.cpp b/window.cpp
index a18f47d70f4c7050f2e4773054f08d84780efe3e..55e08c3c78f0e1a9f15a07d938bd700d7ab621f3 100644
--- a/window.cpp
+++ b/window.cpp
@@ -24,24 +24,24 @@ Window::Window(QWidget *parent)
     m_slider->setValue(m_delay);
     connect(m_slider, SIGNAL(valueChanged(int)), this, SLOT(setValue(int)));
 
-    horizontalLayout = new QHBoxLayout(this);
-    verticalLayout = new QVBoxLayout();
-    layout = new QGridLayout();
+    m_horizontalLayout = new QHBoxLayout(this);
+    m_verticalLayout = new QVBoxLayout();
+    m_layout = new QGridLayout();
 
     m_spacer[0] = new QSpacerItem(4, 4, QSizePolicy::Minimum, QSizePolicy::Fixed);
     m_spacer[1] = new QSpacerItem(4, 4, QSizePolicy::Minimum, QSizePolicy::Fixed);
     m_spacer[2] = new QSpacerItem(8, 8, QSizePolicy::Minimum, QSizePolicy::Expanding);
-    verticalLayout->addItem(m_spacer[2]);
+    m_verticalLayout->addItem(m_spacer[2]);
 
-    verticalLayout->addWidget(m_solveButton);
-    verticalLayout->addWidget(m_slider);
-    verticalLayout->addWidget(m_clearButton);
-    horizontalLayout->addLayout(layout, 5);
-    horizontalLayout->addLayout(verticalLayout, 1);
+    m_verticalLayout->addWidget(m_solveButton);
+    m_verticalLayout->addWidget(m_slider);
+    m_verticalLayout->addWidget(m_clearButton);
+    m_horizontalLayout->addLayout(m_layout, 5);
+    m_horizontalLayout->addLayout(m_verticalLayout, 1);
 
-    layout->addItem(m_spacer[0], 3, 3);
-    layout->addItem(m_spacer[1], 7, 7);
-    layout->setSpacing(0);
+    m_layout->addItem(m_spacer[0], 3, 3);
+    m_layout->addItem(m_spacer[1], 7, 7);
+    m_layout->setSpacing(0);
 
     int dx = 0;
     int dy = 0;
@@ -50,7 +50,7 @@ Window::Window(QWidget *parent)
         for (int y = 0; y < 9; y++)
         {
             m_cell[x + y * 9].setParent(this);
-            layout->addWidget(&m_cell[x + y * 9], y + y / 3, x + x / 3);
+            m_layout->addWidget(&m_cell[x + y * 9], y + y / 3, x + x / 3);
             // connecting signals & slots
             for (int d = 0; d < 9; d++) // rows and columns
             {
@@ -88,20 +88,20 @@ void Window::solveButtonClicked()
         delay(m_delay);
         if (backtracking)
         {
-            hist.back().cell->un();
-            if (hist.back().index.size() == 0)
+            hist.back().cell->collapsedCellClicked();
+            if (hist.back().options.size() == 0)
             {
                 hist.pop_back();
                 continue;
             }
             backtracking = false;
-            int choiceNr = rand() % hist.back().index.size(); // choose a random number;
+            int choiceNr = rand() % hist.back().options.size(); // choose a random number;
             repaint();                                         // draw cells again
             delay(m_delay);
-            hist.back().cell->collapse(hist.back().index[choiceNr]); // collapse cell with chosen number;
+            hist.back().cell->collapse(hist.back().options[choiceNr]); // collapse cell with chosen number;
             std::vector<int>::iterator it;
-            it = hist.back().index.begin() + choiceNr;
-            hist.back().index.erase(it);
+            it = hist.back().options.begin() + choiceNr;
+            hist.back().options.erase(it);
         }
         else
         {
@@ -138,12 +138,11 @@ void Window::solveButtonClicked()
             }
 
             int choiceCell = rand() % b.size();                  // choose a random cell
-            int choiceNr = rand() % b[choiceCell]->index.size(); // choose a random number;
-            hist.push_back(History(b[choiceCell], b[choiceCell]->index, choiceNr));
-            b[choiceCell]->collapse(b[choiceCell]->index[choiceNr]); // collapse that random cell with chosen number;
+            int choiceNr = rand() % b[choiceCell]->options.size(); // choose a random number;
+            hist.push_back(History(b[choiceCell], b[choiceCell]->options, choiceNr));
+            b[choiceCell]->collapse(b[choiceCell]->options[choiceNr]); // collapse that random cell with chosen number;
         }
     }
-    // qInfo("%d---:)");
 }
 inline void Window::delay(int millisecondsWait)
 {
@@ -158,7 +157,7 @@ void Window::clearButtonClicked()
     for (auto &x : m_cell)
     {
         if (x.collapsed)
-            x.un();
+            x.collapsedCellClicked();
     }
     return;
 }
diff --git a/window.h b/window.h
index 421675e595ebdd88f59978ad0c56cdc83091c390..51373e4c7141db8ccbe7745fad83e3fbdafcbf28 100644
--- a/window.h
+++ b/window.h
@@ -22,13 +22,13 @@ private:
     std::array<Cell, 81> m_cell;
     int m_delay = 300;
     QSpacerItem *m_spacer[3];
-    QHBoxLayout *horizontalLayout;
-    QVBoxLayout *verticalLayout;
-    QGridLayout *layout;
+    QHBoxLayout *m_horizontalLayout;
+    QVBoxLayout *m_verticalLayout;
+    QGridLayout *m_layout;
     struct History
     {
         Cell *cell;
-        std::vector<int> index;
+        std::vector<int> options;
         History(Cell *c, std::vector<int> in, int choice)
         {
             cell = c;
@@ -36,7 +36,7 @@ private:
             {
                 if (i == choice)
                     continue;
-                index.push_back(in[i]);
+                options.push_back(in[i]);
             }
         }
     };