Keras で ORの学習

import numpy as np
import keras
from keras.utils import np_utils
from keras.models import Sequential
from keras.layers import Dense

model = Sequential()
model.add(Dense(input_dim=2, activation='relu', units=1))

model.compile(loss='mean_squared_error', optimizer='sgd', metrics=['accuracy'])

# データセット
x_train = [
    [0, 0],
    [0, 1],
    [1, 0],
    [1, 1],
]
# 正解ラベル
y_train = [[0],[1],[1],[1]]

model.fit(x_train, y_train, nb_epoch=10, batch_size=1)
score = model.evaluate(x_train, y_train, verbose=0)
print("test-accuracy: {}".format(score[1]))